TITANIUM-BASED ALLOY COMPOSITION AND METALLIC GLASS CAST ALLOY FORMED THEREFROM

Abstract

Provided herein are Titanium-based metallic glasses (TBMGs) alloys composition in the (TiZrHf)x(CuNi)y(SnSi)z pseudo-ternary system. A method of casting such alloys compositions is also disclosed.

Description

ACKNOWLEDGMENT OF GOVERNMENT SUPPORT

This invention was made with government support under Contract No. 2221854 awarded by the National Science Foundation. The government has certain rights in the invention.

FIELD

The present disclosure is directed to titanium-based alloy compositions having a (TiZrHf)_x(CuNi)_y(SnSi)_z pseudo-ternary system designed for use in manufacturing metallic glass cast alloys.

BACKGROUND

Metallic glasses (MGs) are next-generation metals/alloys that possess an overall disordered atomic structure (with short-range ordering but no long-range translational or rotational symmetry). Among the many different types of MGs, Ti-based MGs (“TBMGs”) are particularly attractive because of their added advantages of being light weight and biocompatible, and their ability to exhibit high specific strength and exceptional corrosion resistance. TBMGs possess great potential to be used in biomedical devices (including human body implants) and aerospace components. While efforts have been made to develop new TBMG alloys, the current TBMGs are plagued by their poor glass-forming ability (GFA) and/or their need for toxic components. As such, new TBMG compositions are needed in the art.

SUMMARY

Disclosed herein is an alloy composition having a formula (TiZrHf)_x(CuNi)_y(SnSi)_z, wherein x ranges from 54 to 56, y ranges from 38.5 to 42.5, and z ranges from 3.5 to 5.5, and each of x, y, and z represents at. %. Also disclosed is a metallic glass cast alloy made from the alloy composition according to the present disclosure.

Further disclosed is a method for making an alloy composition according to the present disclosure, the method comprising: selecting raw metals to provide an alloy composition having a formula (TiZrHf)_x(CuNi)_y(SnSi)_z, wherein x ranges from 54 to 56, y ranges from 38.5 to 42.5, and z ranges from 3.5 to 5.5, and each of x, y, and z represents at. %; cleaning the raw metals with an organic cleaning agent; and melting the raw metals together to form the alloy composition.

Also disclosed is a method for making a metallic glass cast alloy according to the present disclosure, the method comprising: selecting raw metals to provide an alloy composition having a formula (TiZrHf)_x(CuNi)_y(SnSi)_z, wherein x ranges from 54 to 56, y ranges from 38.5 to 42.5, and z ranges from 3.5 to 5.5, and each of x, y, and z represents at. %; cleaning the raw metals with an organic cleaning agent; melting the raw metals together to form the alloy composition; remelting the alloy composition; and tilt casting the alloy composition into a mold to form the metallic glass cast alloy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows X-ray diffraction patterns for an object obtained from casting an alloy composition according to the present disclosure (Ti_42.1Zr_4.3Hf_8.6Cu_40.5-cNi_cSn_3.2Si_1.3) with varied Ni content and cast diameter.

FIG. 2 shows a series of differential scanning calorimetry (DSC) scans at constant heating rate (0.333 K/s) of a cast alloy made with the following alloy compositions according to the disclosure: Ti_42.1Zr_4.3Hf_8.6Cu_35.5Ni₅Sn_3.2Si_1.3, Ti_42.1Zr_4.3Hf_8.6Cu₃₃Ni_7.5Sn_3.2Si_1.3, Ti_42.1Zr_4.3Hf_8.6Cu_31.5Ni₉Sn_3.2Si_1.3, Ti_42.1Zr_4.3Hf_8.6Cu_28.3Ni_12.2Sn_3.2Si_1.3, Ti_42.1Zr_4.3Hf_8.6Cu₂₇Ni_13.5Sn_3.2Si_1.3 and Ti_45.1Zr_3.3Hf_6.6Cu₃₃Ni_7.5Sn_3.2Si_1.3.

FIG. 3 shows differential scanning calorimetry (DSC) scans of a cast alloy made from an alloy composition according to the disclosure (Ti_42.1Zr_4.3Hf_8.6Cu_28.3Ni_12.2Sn_3.2Si_1.3) with six different heating rates, showing the shift of the first crystallization peak.

FIG. 4 is a Kissinger plot obtained from using the heating rate and peak temperature data obtained from FIG. 3, wherein the dashed line indicates a linear fit of the data.

FIG. 5 is a graph showing compressive stress-strain behaviors of various cast alloys made from alloy compositions according to the present disclosure (Ti_42.1Zr_4.3Hf_8.6Cu_35.5Ni₅Sn_3.2Si_1.3, Ti_42.1Zr_4.3Hf_8.6Cu₃₃Ni_7.5Sn_3.2Si_1.3, Ti_42.1Zr_4.3Hf_8.6Cu_31.5Ni₉Sn_3.2Si_1.3, Ti_42.1Zr_4.3Hf_8.6Cu_28.3Ni_12.2Sn_3.2Si_1.3, Ti_45.1Zr_3.3Hf_6.6Cu₃₃Ni_7.5Sn_3.2Si_1.3), wherein the inset provides an optical micrograph of fracture surface of the alloy obtained from the alloy composition of Ti_45.1Zr_3.3 Hf_6.6Cu₃₃Ni_7.5Sn_3.2Si_1.3.

DETAILED DESCRIPTION

I. Explanation of Terms and Definitions

The following explanations of terms are provided to better describe the present disclosure and to guide those of ordinary skill in the art to practice the present disclosure. As used herein, “comprising” means “including.” The singular forms “a” or “an” or “the” include plural references unless the context clearly dictates otherwise. The term “or” refers to a single element of stated alternative elements or a combination of two or more elements, unless the context clearly indicates otherwise.

Unless explained otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used to practice or test the present disclosure, suitable methods and materials are described below. The materials, methods, and examples are illustrative only and are not to be construed as limiting the scope of the invention to the particular disclosed materials, methods and examples. Other features of the disclosure will be apparent to a person of ordinary skill in the art from the following detailed description and the claims.

Disclosed numerical ranges refer to each discrete point within the range, inclusive of endpoints, unless otherwise noted.

Unless otherwise indicated, all numbers expressing quantities of components, molecular weights, percentages, temperatures, times, and so forth, as used in the specification or claims are to be understood as being modified by the term “about.” Accordingly, unless otherwise implicitly or explicitly indicated, or unless the context is properly understood by a person of ordinary skill in the art to have a more definitive construction, the numerical parameters set forth are approximations that may depend on the desired properties sought and/or limits of detection under standard test conditions/methods as known to those of ordinary skill in the art. When directly and explicitly distinguishing embodiments from discussed prior art, the embodiment numbers are not approximations unless the word “about” is recited.

Alloy: A solid or liquid mixture of two or more metals, or of one or more metals with certain nonmetallic elements (e.g., carbon steels).

Alloy Composition: A composition comprising alloying elements described for pseudo-ternary systems according to the present disclosure that can be used to form metallic glass cast alloys. This term typically is used to refer to the composition prior to any casting.

Amorphous: Non-crystalline, having no or substantially no lattice structure. Some solids or semisolids, such as oxide glasses, rubber, and some polymers, are also amorphous. Amorphous solids and semisolids lack a definite crystalline structure.

Cast Alloy: An alloy product obtained after casting an alloy composition according to the present disclosure. The cast alloy is a metallic glass alloy and exhibits one or more properties described herein.

Measured Amount: An amount of an alloy component (e.g., an element) present in an alloy composition and/or a cast alloy according to the present disclosure as determined by evaluating an alloy composition or a cast alloy using a suitable technique, such as inductively coupled plasma, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and other techniques known in the art with the benefit of the present disclosure. In some embodiments, the measured amount of an alloy component may be different from a nominal amount of that alloy component, but typically not by an amount that deleteriously affects the chemical, physical, and/or mechanical properties of a cast alloy formed therefrom.

Metallic glass (MG): A non-crystalline solid alloy that possesses an overall disordered atomic structure, typically with short-range ordering but no long-range translational or rotational symmetry. Metallic glass cast alloys according to the present disclosure are obtained after one or more melting steps wherein ingots of the alloy metals are combined and/or after casting an alloy composition described herein. An MG has a definable melting point because it first transforms to crystals upon heating, and then the crystals are melted upon further heating. An MG behaves (chemically and/or physically) different than a crystalline alloy (including high entropy alloys) when responding to external stimuli. For example, upon mechanical loading, an MG shows much higher (e.g., by several hundred percent) strength, hardness, elastic strain limit, and wear resistance. And, upon reheating, an MG can undergo glass transition, softening and superplastic flow far below the melting temperature. And, upon casting from the molten state, an MG can acquire a pre-designed shape, without suffering from crystallization shrinkage.

I. Introduction

Most current TBMGs must be manufactured with at least one dimension (the shortest one) kept below 6 mm to obtain a fully glassy structure. This threshold in the shortest dimension is termed as the critical casting diameter (for a cylinder) or thickness (for a plate), often referred to as the “dc.” Exceeding the de will result in partial or complete crystallization (due to insufficient cooling rate). Other types of metallic glass cast alloys (e.g., Zr-based, Fe-base, Cu-based, or Hf-based alloys) have been shown to have a de exceeding 10 mm. In contrast, however, only certain TBMGs alloys, e.g., Ti—Zr—Cu—Fe(Ni)—Be and Ti—Zr—Cu—Pd—Sn systems, have been found to reach above the 10 mm benchmark. Unfortunately, these alloys contain substantial amounts of the toxic element, Be; or they require precious metals, like Pd or Ag, and thus are associated with drawbacks like toxicity and/or high cost.

The present disclosure concerns an alloy composition and cast alloys that are metallic glasses formed therefrom that exhibit de values that are not achieved by other titanium-based metallic glasses in the art. And, the disclosed alloy composition avoids toxic elements and/or precious metals. Also disclosed are methods of making and using the disclosed alloy composition and cast alloys formed therefrom.

II. Alloy Composition and Cast Alloy

Alloy compositions according to the present disclosure, and cast alloys/metallic glasses formed therefrom, can comprise a pseudo-ternary system of elements formed from combining different elements from at least three different Groups of the periodic table. In particular aspects of the disclosure, the pseudo-ternary system comprises two or more elements from Group 4, an element from Group 10, an element from Group 11, and two or more elements from Group 14 of the periodic table. In particular aspects, the pseudo-ternary system comprises Ti, Zr, Hf, Cu, Ni, Sn, and Si. In particular aspects, the pseudo-ternary system comprises a combination of these metals having a formula (TiZrHf)—(CuNi)—(SnSi). In some aspects, the alloy composition has a formula (TiZrHf)_x(CuNi)_y(SnSi)_z, wherein x ranges from 54 to 56, y ranges from 38.5 to 42.5, and z ranges from 3.5 to 5.5 and each of x, y, and z represents atomic percent (or “at. %”).

In certain aspects of the alloy composition, the amounts of the elements of the (TiZrHf)—(CuNi)—(SnSi) system are selected according to a formula Ti_x-a-bZr_aHf_bCu_y-cNi_cSn_z-dSi_d, wherein x ranges from 54 to 56, y ranges from 38.5 to 42.5, z ranges from 3.5 to 5.5, “a” ranges from 3 to 4.5, “b” ranges from 6 to 10, “c” ranges from 4 to 15, and “d” ranges from 0.8 to 1.8, with values being expressed as atomic percent (“at. %”). In some aspects, x is 55, y is 40.5, z is 4.5, and d is 1.3. In particular aspects, the alloy composition has a formula according to Ti_55-a-bZr_aHf_bCu_40.5-cNi_cSn_4.5-dSi_d, wherein 3<a<4.5, 6<b<10, 4<c<15 and 0.8<d<1.8, wherein each of a, b, c and d represents at. %. In certain aspects of the pseudo-ternary system, “a” ranges from 3.3 to 4.5, such as 3.3, 4.3, or 4.5 at. %. In certain aspects of the pseudo-ternary system, “b” ranges from 6.6 to 10, such as 6.6, 8.6, or 10 at. %. In certain aspects of the pseudo-ternary system, “c” ranges from 5 to 15, such as 5, 7.5, 9, 12.2, 13.5, or 15 at. %. In certain aspects of the pseudo-ternary system, “d” ranges from 1 to 1.8, such as 1, 1.3, 1.5, or 1.8 at. %. In some aspects, the amounts of Zr and Hf that are included in the alloy are selected to provide a Zr: Hf atomic ratio of 1:2.

In some aspects, the alloy composition may comprise additional elements. Such additional elements can be affirmatively added to the alloy composition or they may be present as impurities in the composition. Such additional elements are not considered to impart any measurable impact on properties of a metallic glass formed from the alloy composition. Additional elements could include Mn, Fe, Co, Ni, Pd, Pt, Au, Y, V, Nb, Ta, Cr, Mo, W, B, Ge, Sb, or combinations thereof. Typically, such elements are included in amounts lower than 1 at. %, either individually or combined.

In some aspects of the disclosure, the alloy composition is selected from Ti_42.1Zr_4.3Hf_8.6Cu_35.5Ni₅Sn_3.2Si_1.3; Ti_42.1Zr_4.3Hf_8.6Cu₃₃Ni_7.5Sn_3.2Si_1.3; Ti_42.1Zr_4.3Hf_8.6 Cu_31.5Ni₉Sn_3.2Si_1.3; Ti_42.1Zr_4.3Hf_8.6Cu₂₇Ni_13.5Sn_3.2Si_1.3; Ti_45.1Zr_3.3Hf_6.6Cu₃₃Ni_7.5Sn_3.2Si_1.3; or Ti_42.1Zr_4.3Hf_8.6Cu_28.3Ni_12.2Sn_3.2Si_1.3.

Metallic glass cast alloys obtained from the disclosed alloy compositions exhibit glass-forming ability (GFA). The metallic glass cast alloys comprise an amorphous atomic structure, typically across all dimensions of the alloy. In some aspects, the metallic glass cast alloy has an atomic structure that is at least 50% amorphous by volume, such as at least 75% amorphous by volume, or at least 80% amorphous by volume, or at least 90% amorphous by volume, or 100% amorphous by volume. The level/percentage of amorphous content of the atomic structure of the metallic glass cast alloy can be accurately determined by measuring crystallization enthalpy upon heating in a calorimeter. In some aspects, the smallest dimension of the metallic glass cast alloy is greater than 4 mm to 15 mm, such as 4 mm to 15 mm, 5 mm to 15 mm, 6 mm to 15 mm, 7 mm to 15 mm, 8 mm to 15 mm, 9 mm to 15 mm, 10 mm to 15 mm, or 11 mm to 15 mm. In some aspects, the smallest dimension of the metallic glass cast alloy ranges from 6 mm to 12 mm, 7 mm to 12 mm, 8 mm to 12 mm, 9 mm to 12 mm, 10 mm to 12 mm, or 11 mm to 12 mm. In some aspects, the metallic glass cast alloys are produced as cylindrical cast rods that can exhibit critical casting diameters values (dc) ranging from greater than 4 mm to 15 mm, such as 4 mm to 15 mm, 5 mm to 15 mm, 6 mm to 15 mm, 7 mm to 15 mm, 8 mm to 15 mm, 9 mm to 15 mm, 10 mm to 15 mm, or 11 mm to 15 mm. In some aspects, the de ranges from 6 mm to 12 mm, 7 mm to 12 mm, 8 mm to 12 mm, 9 mm to 12 mm, 10 mm to 12 mm, or 11 mm to 12 mm. In some aspects, the de can range from 8 mm to 12 mm. In some aspects, the alloy compositions disclosed herein are used to arrive at titanium-based metallic glass cast alloys that exhibit the largest known de values to date obtained from a titanium alloy composition that is free of toxic elements like Be, Cd, Pb, and As, and/or precious metals (e.g., Pd, Pt, Au, Ag, and the like).

In particular aspects when the alloy composition is cast to provide a cast metallic glass alloy, the cast metallic glass alloy can have any desired shape. In some aspects, the alloy composition is tilt cast into copper molds to form cylindrical rods of various diameters. Such rods can be used for evaluating critical casting diameter values, as discussed above. In some aspects, the molten alloy composition (or the molten metallic glass alloy) can be formed into an article having other shapes (e.g., square rods, screws, gears, and the like) by casting the alloy composition into a pre-made mold having the desired shape.

The metallic glass cast alloy according to the present disclosure exhibits desirable properties. In some aspects, the metallic glass cast alloy exhibits a density ranging from 7 g/cm³ to 8 g/cm³, such as 7.3 g/cm³ to 8 g/cm³. In some aspects, the metallic glass cast alloy exhibits a Vickers hardness ranging from 590 kg/mm² to 620 kg/mm², such as 590 kg/mm² to 615 kg/mm², or 600 kg/mm² to 615 kg/mm². In some aspects, the metallic glass cast alloy exhibits a yield strength ranging from 1.9 GPa to 2.1 GPa, such as 1.94 GPa to 2.1 GPa, or 1.96 GPa to 2.1 GPa. In some aspects, the metallic glass cast alloy exhibits a fracture strength ranging from 2 GPa to 3 GPa, such as 2.4 GPa to 2.8 GPa, or 2.4 GPa to 2.6 GPa. In some aspects, the metallic glass cast alloy exhibits a specific fracture strength ranging from 320 N m/g to 370 N m/g, such as 325 N m/g to 360 N m/g, or 350 N m/g to 360 N m/g. In some aspects, the metallic glass cast alloy exhibits a plastic strain (at fracture) ranging from 2.5% to 9.5%, such as 3% to 8%, or 3% to 6%. In some aspects, the metallic glass cast alloy exhibits a glass transition temperature ranging from 675 K to 700 K, such as 675 K to 695 K or 680 K to 695 K. In some aspects, the metallic glass cast alloy exhibits an onset crystallization temperature ranging from 720 K to 740 K, such as 725 K to 740 K. Exemplary alloy compositions used to make exemplary metallic glass cast alloys according to the present disclosure are described in Table 1 of the Examples, along with properties observed for the metallic glass cast alloys formed from the compositions.

III. Method of Making Alloy Composition and Cast Alloy

The alloy compositions and metallic glass cast alloys described herein can be made by metal/alloy fabrication steps/methods, which will be recognized by those in the art with the benefit of the present disclosure. In some aspects, the alloy composition disclosed herein is designed to be compatible with casting methods, such as tilt casting. In particular aspects, the alloy compositions are made by weighing constituent species (i.e. raw metals) according to the alloy composition using a precision balance; cleaning the raw metals with an organic solvent, such as acetone and then ethanol in an ultrasonic cleaner for at least 5 minutes to obtain ultrasonically cleansed Ti (99.9+%, crystal bar), Zr (99.9+%, crystal bar), Hf (99.2+%, crystal bar), Cu (99.99%, oxygen-free shot), Ni (99.98%, slugs), Sn (99%, shot), and Si (99.9+% lump) pieces; and melting the raw metals together to form a uniform alloy composition using an arc melter under protective atmosphere (e.g. ultrahigh purity Argon). Prior to the melting of the raw materials, the arc melter chamber is vacuumed to 3×10⁻⁴ mbar residual pressure and filled with ultrahigh purity (UHP) argon. A sacrificial metal, such as a Zr-getter, is first melted to absorb the remaining oxygen and further clean the atmosphere. The alloy ingots are flipped and re-melted at least eight times to acquire complete chemical homogeneity. Then, the ingots are melted again and the alloy composition is tilt cast into a copper mold placed underneath the melting stage to form the metallic glass cast alloy (e.g., such as in cylindrical rods of various diameters). Other suitable casting methods also could be used, including injection casting, die casting, and suction casting. In yet other aspects, the alloy composition can be added to a refractory mold and cooled with the mold using water quenching. The structure of the metallic glass cast alloy after casting can be analyzed using XRD. The thermal behaviors of the metallic glass cast alloy can be evaluated with DSC. Vickers hardness can be measured using pyramid-shaped indenter on the metallic glass cast alloy. And, densities can be determined with an OHAUS PA84 and Density measurement kit.

IV. Overview of Several Aspects

Disclosed herein is an alloy composition having a formula (TiZrHf)_x(CuNi)_y(SnSi)_z, wherein x ranges from 54 to 56, y ranges from 38.5 to 42.5, and z ranges from 3.5 to 5.5, and each of x, y, and z represents at. %.

In any or all aspects, the alloy composition has a formula Ti_x-a-bZr_aHf_bCu_y-cNi_cSn_z-dSi_d, wherein a ranges from 3 to 4.5, b ranges from 6 to 10, c ranges from 4 to 15, and d ranges from 0.8 to 1.8, and each of a, b c, and d represents at. %.

In any or all of the above aspects, the alloy composition has a formula Ti_55-a-bZr_aHf_bCu_40.5-cNi_cSn_4.5-dSi_d, wherein a ranges from 3 to 4.5, b ranges from 6 to 10, c ranges from 4 to 15, and d ranges from 0.8 to 1.8, and wherein each of a, b, c, and d represents at. %.

In any or all of the above aspects, a ranges from 3.3 at. % to 4.5 at. %; b ranges from 6.6 at. % to 10 at. %; c ranges from 5 at. % to 15 at. %; d ranges from 1 at. % to 1.8 at. %.

In any or all of the above aspects, a is 3.3 or 4.3; b is 6.6 or 8.6; c is 5, 7.5, 9, 12.2, or 13.5; and d is 1.3 or 1.5.

In any or all of the above aspects, a is 4.3; b is 8.6; c is 12.2; and d is 1.3.

In any or all of the above aspects, the atomic ratio of Zr:Hf is 1:2.

In any or all of the above aspects, the alloy composition has a formula selected from: Ti_42.1Zr_4.3Hf_8.6Cu_35.5Ni₅Sn_3.2Si_1.3; Ti_42.1Zr_4.3Hf_8.6Cu₃₃Ni_7.5Sn_3.2Si_1.3; Ti_42.1Zr_4.3Hf_8.6Cu_31.5Ni₉Sn_3.2Si_1.3; Ti_42.1Zr_4.3Hf_8.6Cu₂₇Ni_13.5Sn_3.2Si_1.3; Ti_45.1Zr_3.3Hf_6.6Cu₃₃Ni_7.5Sn_3.2Si_1.3; or Ti_42.1Zr_4.3Hf_8.6Cu_28.3Ni_12.2Sn_3.2Si_1.3.

In any or all of the above aspects, the alloy composition has the formula Ti_42.1Zr_4.3Hf_8.6Cu_28.3Ni_12.2Sn_3.2Si_1.3.

Also disclosed herein is a metallic glass cast alloy made from the alloy composition according to any or all of the above composition aspects.

In any or all of the above aspects, the metallic glass cast alloy is at least 75% amorphous by volume.

In any or all of the above aspects, the metallic glass cast alloy is at least 90% amorphous by volume.

In any or all of the above aspects, the metallic glass cast alloy is three dimensional and the smallest dimension of the metallic glass cast alloy ranges from 4 mm to 15 mm.

In any or all of the above aspects, the metallic glass cast alloy is cast in the shape of a cylindrical rod and the cylindrical rod has a critical casting diameter ranging from 4 mm to 15 mm.

In any or all of the above aspects, the metallic glass cast alloy is three dimensional and the smallest dimension of the metallic glass cast alloy ranges from 8 mm to 12 mm.

In any or all of the above aspects, the metallic glass cast alloy has one or more of the following properties:

• • (i) a Vickers hardness (H_v) value ranging from 590 kg/mm² to 620 kg/mm²;
  • (ii) a yield strength ranging from 1.90 GPa to 2.1 GPa;
  • (iii) a fracture strength ranging from 2 GPa to 3 GPa;
  • (iv) a specific fracture strength ranging from 320 N m/g to 370 N m/g;
  • (v) a plastic strain ranging from 2.5% to 9.5%;
  • (vi) a density ranging from 7 g/cm³ to 8 g/cm³; or
  • (vii) any combination of two or more of (i), (ii), (iii), (iv), (v), and (vi).

In any or all of the above aspects, the metallic glass cast alloy has a glass transition temperature ranging from 675 K to 700 K and/or an onset crystallization temperature ranging from 720 K to 740 K.

Also disclosed is a method for making an alloy composition according to any or all of the above composition aspects, comprising: selecting raw metals to provide an alloy composition having a formula (TiZrHf)_x(CuNi)_y(SnSi)_z, wherein x ranges from 54 to 56, y ranges from 38.5 to 42.5, and z ranges from 3.5 to 5.5, and each of x, y, and z represents at. %; cleaning the raw metals with an organic cleaning agent; and melting the raw metals together to form the alloy composition.

In any or all of the above method aspects, the alloy composition has a formula Ti_x-a-bZr_aHf_bCu_y-cNi_cSn_z-dSi_d, wherein a ranges from 3 to 4.5, b ranges from 6 to 10, c ranges from 4 to 15, and d ranges from 0.8 to 1.8, and wherein each of a, b, c and d represents at. %.

Also disclosed is a method for making a metallic glass cast alloy, the method comprising: selecting raw metals to provide an alloy composition having a formula (TiZrHf)_x(CuNi)_y(SnSi)_z, wherein x ranges from 54 to 56, y ranges from 38.5 to 42.5, and z ranges from 3.5 to 5.5, and each of x, y, and z represents at. %; cleaning the raw metals with an organic cleaning agent; melting the raw metals together to form the alloy composition; remelting the alloy composition; and tilt casting the alloy composition into a mold to form the metallic glass cast alloy.

V. Examples

The following examples are provided to illustrate certain features of exemplary embodiments. Those in the art will appreciate that the scope of the invention is not limited to these exemplary features.

Example 1

In this example, methods for making alloy compositions and metallic glass cast alloys are described. According to a representative method, alloy ingots of different compositions were prepared through arc-melting mixtures of ultrasonically cleansed Ti (99.9+%, crystal bar), Zr (99.9+%, crystal bar), Hf (99.2+%, crystal bar), Cu (99.99%, oxygen-free shot), Ni (99.98%, slugs), Sn (99%, shot), and Si (99.9+% lump) pieces. Prior to the melting of the raw materials, the arc melter chamber was vacuumed to ~3×10⁻⁴ mbar residual pressure and filled with ultrahigh purity (UHP) argon, and then a Zr-getter was used (melted) to absorb the remaining oxygen and further clean the atmosphere. The alloy ingots were flipped and re-melted at least eight times each to acquire complete chemical homogeneity. Then, the ingots were melted again and tilt cast into a copper mold placed underneath the melting stage to form cylindrical rods of various diameters. Cross-sections of the cast rods were analyzed with an X-ray diffractometer (Rigaku Smartlab) using a Cu—K_α source to reveal the amorphous or crystalline structure. Thermal behaviors, including glass transition and crystallization, of the alloys were studied with a differential scanning calorimeter (DSC, Mettler Toledo DSC3) at a heating rate of 0.333 K/s in a flowing nitrogen atmosphere. DSC scans at additional heating rates (0.083, 0.167, 0.333, 0.500, 0.667, and 0.833 K/s) were conducted to obtain the crystallization activation energy based on the Kissinger method. Compression tests were performed on specimens of ~1.35 mm diameter and 2.7 mm length using the Deben MT5000 (maximum load: 5 kN) test module at a nominal strain rate of ~6×10⁻⁴ s⁻¹. Vickers hardness was measured on a LECO M400A microhardness tester using a pyramid-shaped indenter, a 500 gf load and a 15 s dwelling time. Densities were determined according to the Archimedes' Principle using the Pioneer Scale—OHAUS PA84 and Density measurement kit. Compositions described in Tables 1A and 1B, below, were prepared.

TABLE 1A
Alloy composition	dc	ρ	Hv	σy
(in at. %)	(mm)	(g/cm3)	(kg/mm2)	(GPa)
Ti42.1Zr4.3Hf8.6Cu35.5Ni5Sn3.2Si1.3	8	7.3	594	1.94
Ti42.1Zr4.3Hf8.6Cu33Ni7.5Sn3.2Si1.3	≥8	7.3	606	1.98
Ti42.1Zr4.3Hf8.6Cu31.5Ni9Sn3.2Si1.3	≥8	7.3	609	1.99
Ti42.1Zr4.3Hf8.6Cu28.3Ni12.2Sn3.2Si1.3	12	7.3	611	2.00
Ti42.1Zr4.3Hf8.6Cu27Ni13.5Sn3.2Si1.3	10	7.3	615	2.01
Ti45.1Zr3.3Hf6.6Cu33Ni7.5Sn3.2Si1.3	8	7.0	595	1.94

TABLE 1B
		σf, s
Alloy composition	σf	(N	εp	Tg	Tx
(in at. %)	(GPa)	m/g)	(%)	(K)	(K)
Ti42.1Zr4.3Hf8.6Cu35.5Ni5Sn3.2Si1.3	2.6	356	3.9	675	726
Ti42.1Zr4.3Hf8.6Cu33Ni7.5Sn3.2Si1.3	2.4	329	2.8	679	730
Ti42.1Zr4.3Hf8.6Cu31.5Ni9Sn3.2Si1.3	2.7	370	6.1	680	729
Ti42.1Zr4.3Hf8.6Cu28.3Ni12.2Sn3.2Si1.3	2.6	356	3.1	691	736
Ti42.1Zr4.3Hf8.6Cu27Ni13.5Sn3.2Si1.3	—	—	—	692	735
Ti45.1Zr3.3Hf6.6Cu33Ni7.5Sn3.2Si1.3	2.5	357	9.4	677	728

Example 2

In this example, cross-sections of the cast rods obtained from Example 1 were analyzed with an X-ray diffractometer (Rigaku Smartlab) using a Cu-K_α source to reveal the amorphous or crystalline structure of the metallic glasses. FIG. 1 presents the X-ray diffraction (XRD) patterns of the cast rods of Ti_42.1Zr_4.3Hf_8.6Cu_40.5-cNi_cSn_3.2Si_1.3 alloys with varied Ni content, where c=5, 7.5, 9, 12.2, and 13.5 and diameters such as 8, 10 and 12 mm. These patterns only exhibit diffuse maxima, without any sharp Bragg peaks. This ascertains the fully amorphous nature of the cast rods. In the previous research on TBMGs, fully amorphous structure at these diameters was obtained only for alloys containing substantial amounts of the toxic Be or the precious metal Pd. A representative alloy composition according to the present disclosure, Ti_42.1Zr_4.3Hf_8.6Cu_28.3Ni_12.2Sn_3.2Si_1.3, with a de of 12 mm, stands out as the non-toxic and precious-metal free TBMG with the highest GFA and manufacturability.

Example 3

In this example, thermal behaviors of the TBMGs, including glass transition and crystallization, of the alloys are studied with a differential scanning calorimeter (DSC, Mettler Toledo DSC3) at a heating rate of 0.333 K/s in a flowing nitrogen atmosphere. As shown in FIG. 2, the TBMGs compositions shown in Table 1 all exhibit a clear glass transition, indicated by a downslope (endothermic) of the heat flow curve between 650 and 700 K, and multiple crystallization events signified by the up-pointing (exothermic) peaks above 720 K. The values of the glass transition temperature T_g and the onset crystallization (first event) temperature T_x, as determined by the commonly used two-tangent method, are listed in Table 1. The width of supercooled liquid region ΔT=T_x−T_g falls in the range of 43 K to 51 K. As the composition is varied, the T_g exhibits an increasing trend as more Cu is substituted with Ni (all other elemental contents fixed). This is similar to the trend in hardness across these compositions, which will be discussed in Example 4, and reflects the fundamental dependence of T_g on the chemical interaction (bond strength) among the constituent elements.

The activation energy of the thermally activated process is obtained using the Kissinger method. This technique involves analyzing the correlation between the peak temperature of the process on a DSC scan and the heating rate used. FIG. 3 shows the first (primary) crystallization event recorded by DSC at six different heating rates from 0.0833 K/s to 0.8333 K/s, such as 0.083, 0.167, 0.333, 0.500, 0.667, and 0.833 K/s for the composition Ti_42.1Zr_4.3Hf_8.6Cu_28.3Ni_12.2Sn_3.2Si_1.3.

A higher heating rate (β) leads to an increase in the peak temperature (T_p) as expected. According to the Kissinger method, the relationship between β and T_p can be reduced to:

$\ln \left(\frac{\beta }{T_p^2}\right)=-\frac{E_a}{R}\frac{1}{T_p}+\mathrm{contant},$

that is, a linear correlation between

$\ln \left(\frac{\beta }{T_p^2}\right)\mathrm{and}\frac{1}{T_p},$

with the slope equal to

$-\frac{E_{\alpha }}{R}$

(where E_a is the activation energy, and R is the ideal gas constant). FIG. 4 presents the experimental data (symbols) for

$\ln \left(\frac{\beta }{T_p^2}\right)\mathrm{and}\frac{1}{T_p}$

and the linear fit (dashed line). The data follow the Kissinger model quite closely, as suggested by a high fitting-goodness R²=0.98. From the fitted slope, the activation energy E_a is determined to be 343 KJ/mol. This value is significantly higher than those reported in the art for the first (primary) crystallization event in other TBMGs, for example, 287.6 KJ/mol for Ti₄₀Zr₁₀Cu₃₆Pd₁₄, 179 KJ/mol for Ti₄₁Zr₂₅Be₂₈Fe₆, and 188 KJ/mol for (Ti₄₁Zr₂₅Be₂₈Fe₆)₉₃Cu₇. Since glass formation requires the avoidance of crystallization, the high value of E for crystallization obtained here partially explains the exceptional GFA of the present TBMG.

Example 4

In this example, compression tests are performed on specimens of ~1.35 mm diameter and 2.7 mm length using the Deben MT5000 (maximum load: 5 kN) test module at a nominal strain rate of ~6×10⁻⁴ s⁻¹. Densities of the TBMGs are determined according to the Archimedes' Principle using the Pioneer Scale-OHAUS PA84 and Density measurement kit. Vickers hardness of the TBMGs is measured on a LECO M400A microhardness tester using a pyramid-shaped indenter, a 500 gf load and a 15 s dwelling time. FIG. 5 (main panel) shows the engineering stress-strain curves of five TBMGs in Table 1, obtained through compression tests. All five TBMGs exhibit work hardening and serrated flow after yielding and several percent plastic strain (Ep) before fracture, alluding to the intrinsic plasticity in these glassy alloys. Particularly, the Ti_45.1Zr_3.3Hf_6.6Cu₃₃Ni_7.5Sn_3.2Si_1.3 alloy underwent a 9.4% plastic strain before fracture, which clearly surpasses most of the previously reported TBMGs (including the Be- and Pd-bearing ones and/or those disclosed by Gong et al., Metals, 2016, 6, 264). The fracture surface (inset in FIG. 5) exhibits significant vein-like features and a non-flat terrain with frequent variations in height. These microscopic characteristics indicate the fair amount of resistance experienced by the final crack during its propagation, consistent with the plasticity displayed by the stress-strain curves. The fracture strength (σ_f) of the present alloys' ranges from 2.4 to 2.7 GPa, which is higher than most other TBMGs in the art. The specific fracture strength (σ_f,s=σ_f/ρ), ~330 to 370 Nm g⁻¹, falls in the range typical of TBMGs, and is significantly higher than that of the conventional light-weight alloys Ti-6Al-4V (~217 N m g⁻¹) and AZ91 (~154 N m g⁻¹), or other types of MGs (e.g., Zr-based: 270-310 N m g⁻¹, and Mg-based: ~310 N m g⁻¹).

The densities (ρ, listed in Table 1A) of the alloy compositions of Ti_42.1Zr_4.3Hf_8.6Cu_40.5-c Ni_cSn_3.2Si_1.3, where c=5, 7.5, 9, 12.2, and 13.5 are all measured to be 7.3 g/cm³, insensitive to the partition between the Cu and the Ni contents (due to the similarity of the two elements in their densities). This is close to the known 7.0 g/cm³ of Ti_41.5Zr_2.5Hf₅Cu_37.5Ni_7.5Si₁Sn₅ and 6.85 g/cm³ of the Pd-bearing Ti₄₀Zr₁₀Cu₃₄Pd₁₄Sn₂ TBMGs known in the art.

The Hf content has a strong impact on the alloy density here (due to the high density of Hf). At a lower Hf content, the Ti_45.1Zr_3.3Hf_6.6Cu₃₃Ni_7.5Sn_3.2Si_1.3 alloy reaches a density of 7.0 g/cm³, while still retaining an excellent GFA with dc equal to 8 mm.

Also listed in Table 1A are the Vickers hardness (H_v) values of the present TBMGs, which fall in the range from ~590 to 620 kg/mm². The hardness displays an increasing trend as more Cu is substituted with Ni (all other elemental contents fixed). This is attributable to the stronger interaction of Ni than Cu with the other five elements, as indicated by the more negative heat of mixing (ΔH_mix): −35, −49, −42, −4 and −40 KJ/mol for Ni with Ti, Zr, Hf, Sn, and Si, respectively, as opposed to the −9, −23, −17, 7, −19 for Cu. For a similar reason (Zr and Hf interact more strongly than Ti with other elements), when some of the Zr and Hf percentages are shifted onto Ti while fixing all the other elements, the hardness decreases. The yield strength (σ_y) estimated from the relationship (for isotropic materials)

${\sigma }_y=\frac{H_{\nu }}{3}$

is also listed In Table 1A, which is in reasonable agreement with the compression tests (at 2% elastic strain).

Example 5

In this example, atomic packing efficiency, useful for understanding the origin of GFA of a MG, is calculated based on the measured density data. It is known that MGs with good GFA often possess high atomic packing efficiency (APE). Efficient (dense) atomic packing can increase the viscosity of a supercooled liquid and decrease the atomic mobility and thereby suppress crystallization kinetically. The APE of a MG can be calculated as

$\mathrm{APE}=\rho \times \left(N_A{\sum }_i{c}_i\frac{4\pi }{3}{r}_i^3\right)/\left({\sum }_i{c}_i{m}_i\right),$

where ρ is the density of the alloy, N_A is the Avogadro's number, and c_i, r_i and m_i are the atomic percent, atomic radius and atomic (molar) mass of the ith element, respectively. The APE for the alloy composition Ti_42.1Zr_4.3Hf_8.6Cu_40.5-cNi_cSn_3.2Si_1.3, where c=5, 7.5, 9, 12.2, and 13.5 is calculated (using the atomic radii in Miracle, et al., Philos. Mag. 2003, 83, 2409) and is equal to 0.763, 0.765, 0.766, 0.768, and 0.769, respectively. The APE for the alloy composition Ti_45.1Zr_3.3Hf_6.6Cu₃₃Ni_7.5Sn_3.2Si_1.3 is 0.757. These APE values are all greater than the well-known 0.74 for the close-packed fcc (face-centered-cubic) crystal structure. This reflects the efficient atomic packing in these TBMGs and aligns well with their exceptional GFA.

In view of the many possible aspects to which the principles of the present disclosure may be applied, it should be recognized that the illustrated aspects are only preferred examples of the disclosure and should not be taken as limiting the scope of the present disclosure. Rather, the scope is defined by the following claims. We therefore claim as our invention all that comes within the scope and spirit of these claims.

Claims

1. An alloy composition having a formula (TiZrHf)x(CuNi)y(SnSi)z, wherein x ranges from 54 to 56, y ranges from 38.5 to 42.5, and z ranges from 3.5 to 5.5, and each of x, y, and z represents at. %.

2. The alloy composition according to claim 1, having the formula Tix-a-bZraHfbCuy-cNicSnz-dSid, wherein a ranges from 3 to 4.5, b ranges from 6 to 10, c ranges from 4 to 15, and d ranges from 0.8 to 1.8, and each of a, b c, and d represents at. %.

3. The alloy composition according to claim 1, having the formula Ti55-a-bZraHfbCu40.5-cNicSn4.5-dSid, wherein a ranges from 3 to 4.5, b ranges from 6 to 10, c ranges from 4 to 15, and d ranges from 0.8 to 1.8, and wherein each of a, b, c, and d represents at. %.

4. The metallic glass-forming alloy according to claim 2, wherein a ranges from 3.3 at. % to 4.5 at. %; b ranges from 6.6 at. % to 10 at. %; c ranges from 5 at. % to 15 at. %; d ranges from 1 at. % to 1.8 at. %.

5. The metallic glass-forming alloy according to claim 2, wherein a is 3.3 or 4.3; b is 6.6 or 8.6; c is 5, 7.5, 9, 12.2, or 13.5; and d is 1.3 or 1.5.

6. The metallic glass-forming alloy according to claim 2, wherein a is 4.3; b is 8.6; c is 12.2; and d is 1.3.

7. The metallic glass-forming alloy according to claim 1, wherein the atomic ratio of Zr:Hf is 1:2.

8. The metallic glass-forming alloy according to claim 1, having a formula selected from:

Ti42.1Zr4.3Hf8.6Cu35.5Ni5Sn3.2Si1.3;

Ti42.1Zr4.3Hf8.6Cu33Ni7.5Sn3.2Si1.3;

Ti42.1Zr4.3Hf8.6Cu31.5Ni9Sn3.2Si1.3;

Ti42.1Zr4.3Hf8.6Cu27Ni13.5Sn3.2Si1.3;

Ti45.1Zr3.3 Hf6.6Cu33Ni7.5Sn3.2Si1.3; Or

Ti42.1Zr4.3Hf8.6Cu28.3Ni12.2Sn3.2Si1.3.

9. The metallic glass-forming alloy according to claim 1 having the formula Ti42.1Zr4.3Hf8.6Cu28.3Ni12.2Sn3.2Si1.3.

10. A metallic glass cast alloy made from the alloy composition according to claim 1.

11. The metallic glass cast alloy of claim 10, wherein the metallic glass cast alloy is at least 75% amorphous by volume.

12. The metallic glass cast alloy of claim 10, wherein the metallic glass cast alloy is at least 90% amorphous by volume.

13. The metallic glass cast alloy of claim 10, wherein the metallic glass cast alloy is three dimensional and the smallest dimension of the metallic glass cast alloy ranges from 6 mm to 15 mm.

14. The metallic glass cast alloy of claim 10, wherein the metallic glass cast alloy is cast in the shape of a cylindrical rod and the cylindrical rod has a critical casting diameter ranging from 6 mm to 15 mm.

15. The metallic glass cast alloy of claim 10, wherein the metallic glass cast alloy is three dimensional and the smallest dimension of the metallic glass cast alloy ranges from 8 mm to 12 mm.

16. The metallic glass cast alloy of claim 10, wherein the metallic glass cast alloy has one or more of the following properties:

(i) a Vickers hardness (Hv) value ranging from 590 kg/mm2 to 620 kg/mm2;

(ii) a yield strength ranging from 1.90 GPa to 2.1 GPa;

(iii) a fracture strength ranging from 2 GPa to 3 GPa;

(iv) a specific fracture strength ranging from 320 N m/g to 370 N m/g;

(v) a plastic strain ranging from 2.5% to 9.5%;

(vi) a density ranging from 7 g/cm3 to 8 g/cm3; or

(vii) any combination of two or more of (i), (ii), (iii), (iv), (v), and (vi).

17. The metallic glass cast alloy of claim 10, wherein the metallic glass cast alloy has a glass transition temperature ranging from 675 K to 700 K and/or an onset crystallization temperature ranging from 720 K to 740 K.

18. A method for making an alloy composition according to claim 1, comprising:

selecting raw metals to provide an alloy composition having a formula (TiZrHf)x(CuNi)y(SnSi)z, wherein x ranges from 54 to 56, y ranges from 38.5 to 42.5, and z ranges from 3.5 to 5.5, and each of x, y, and z represents at. %;

cleaning the raw metals with an organic cleaning agent; and

melting the raw metals together to form the alloy composition.

19. The method of claim 18, wherein the alloy composition has a formula Tix-a-bZraHfbCuy-cNicSnz-dSid, wherein a ranges from 3 to 4.5, b ranges from 6 to 10, c ranges from 4 to 15, and d ranges from 0.8 to 1.8, and wherein each of a, b, c and d represents at. %.

20. A method for making a metallic glass cast alloy, the method comprising:

selecting raw metals to provide an alloy composition having a formula (TiZrHf)x(CuNi)y(SnSi)z, wherein x ranges from 54 to 56, y ranges from 38.5 to 42.5, and z ranges from 3.5 to 5.5, and each of x, y, and z represents at. %;

cleaning the raw metals with an organic cleaning agent;

melting the raw metals together to form the alloy composition;

remelting the alloy composition; and

tilt casting the alloy composition into a mold to form the metallic glass cast alloy.