Abstract: A corrodible downhole article includes a magnesium alloy. The magnesium alloy includes: 1-9 wt % Zn; 1-2 wt % Cu; 0.5-1.0 wt % Mn; and 0.1-5 wt % of a corrosion promoting element (e.g., Ni). The alloy can have a 0.2% proof strength of at least 150 MPa when tested using standard tensile test method ASTM B557-10.

Abstract: A magnesium alloy is suitable for use as a corrodible downhole article, wherein the alloy includes: (a) 2-7 wt % Gd, (b) 0-2 wt % Y, (c) 0-5.0 wt % Nd, and (d) at least 80 wt % Mg, and has an elongation as measured by ASTM B557M-10 of at least 22%.

Abstract: A magnesium alloy is suitable for use as a corrodible downhole article, wherein the alloy includes: (a) 11-15 wt % Y, (b) 0.5-5 wt % in total of rare earth metals other than Y, (c) 0-1 wt % Zr, (d) 0.1-5 wt % Ni, and (e) at least 70 wt % Mg. It has been surprisingly found by the inventors that by increasing the Y content of the alloy to the range specified above, increased age hardening response and hence increased 0.2% proof stress can be achieved.

Abstract: A magnesium alloy is suitable for use as a corrodible downhole article, wherein the alloy includes: (a) 11-15 wt % Y, (b) 0.5-5 wt % in total of rare earth metals other than Y, (c) 0-1 wt % Zr, (d) 0.1-5 wt % Ni, and (e) at least 70 wt % Mg. It has been surprisingly found by the inventors that by increasing the Y content of the alloy to the range specified above, increased age hardening response and hence increased 0.2% proof stress can be achieved.

Abstract: A magnesium alloy is suitable for use as a corrodible downhole article, wherein the alloy includes: (a) 2-7 wt % Gd, (b) 0-2 wt % Y, (c) 0-5.0 wt % Nd, and (d) at least 80 wt % Mg, and has an elongation as measured by ASTM B557M-10 of at least 22%.

Abstract: A corrodible downhole article includes a magnesium alloy. The magnesium alloy includes: 1-9 wt % Zn; 1-2 wt % Cu; 0.5-1.0 wt % Mn; and 0.1-5 wt % of a corrosion promoting element (e.g., Ni). The alloy can have a 0.2% proof strength of at least 150 MPa when tested using standard tensile test method ASTM B557-10.

Abstract: A corrodible downhole article includes a magnesium alloy, including: a strengthening metallic element comprising at least one of Al, Zn, Mn, Cu and Ag and at least one corrosion promoting element in an amount of 0.01-10 wt % in total. The alloy has a corrosion rate of at least at least 75 mg/cm2/day in 15% KC1 at 93° C. and a 0.2% proof strength of at least 100MPa when tested using standard tensile test method ASTM B557-10. In particular, the magnesium alloy includes 5-10 wt % Al, and at least one of Zn and Mn in a total amount ranging from 0 to 1.0 wt %.

Abstract: The invention relates to composite sacrificial anodes, particularly but not exclusively, based on magnesium, and to methods for their production. The composite sacrificial anode (10) for immersion in a corrosive environment comprises a plurality of castings (12) of a sacrificial material each disposed around a corresponding electrical connector for attachment to a structure to be protected, at least a part of the surface of each segment (12) being protected from corrosion by the environment by being adjacent at least one other segment (12), wherein the castings are connected together electrically only via their electrical connectors.