Abstract: A most preferred composition for the mixture, prior to sintering into an article (ideally a valve seat insert), is as follows: 35% hard phase, 65% matrix (excepting incidental impurities), the hard phase component being 2.2% C, 29.1% Cr, 4.9% Co, 5.3% Ni, 20.2% W with the balance being Fe and allowing less than 2% for one or more machinability aids and solid lubricants, and the matrix component being one of a high chrome steel powder (e.g. 18% Cr, 1% Ni, 2.5% Mo, balance Fe), a low alloy steel powder (3% Cu, 1% C, balance Fe; 3% Cr, 0.5% Mo, 1% C, balance Fe; 4% Ni, 1.5% Cu, 0.5% Mo, 1% C, balance Fe; 4% Ni, 2% Cu, 1.4% Mo, 1% C, balance Fe), or a tool steel powder (5% Mo, 6% W, 4% Cr, 2% V, 1% C, balance Fe), or a low-alloy steel powder as above but which issued in conjunction with a copper infiltration process during sintering.

Abstract: A most preferred composition for the mixture, prior to sintering into an article (ideally a valve seat insert), is as follows: 35% hard phase, 65% matrix (excepting incidental impurities), the hard phase component being 2.2% C, 29.1% Cr, 4.9% Co, 5.3% Ni, 20.2% W with the balance being Fe and allowing less than 2% for one or more machinability aids and solid lubricants, and the matrix component being one of a high chrome steel powder (e.g. 18% Cr, 1% Ni, 2.5% Mo, balance Fe), a low alloy steel powder (3% Cu, 1% C, balance Fe; 3% Cr, 0.5% Mo, 1% C, balance Fe; 4% Ni, 1.5% Cu, 0.5% Mo, 1% C, balance Fe; 4% Ni, 2% Cu, 1.4% Mo, 1% C, balance Fe), or a tool steel powder (5% Mo, 6% W, 4% Cr, 2% V, 1% C, balance Fe), or a low-alloy steel powder as above but which issued in conjunction with a copper infiltration process during sintering.

Abstract: A sintered material and a method for the production thereof is described. The material comprises an alloy selected from one of the groups having a composition comprising in weight %: either Cr 5-30/Mo 0-15/Ni 0-25/W 0-15/C 0-5/Si 0-5/Fe 0-5/Mn 0-5/others 10 max/Co balance, or Cr 10-20/Mo 0-15/Co 0-20/W 0-5/Fe 0-20/Al 0-5/Ti 0-5/others 15 max/Ni balance; said alloy having incorporated therein from 3-15 weight % of Sn; and optionally from 1-6 weight % of a solid lubricant material.

Abstract: A sintered steel and a method for the manufacture thereof are described, the sintered steel being made by a method comprising the steps of providing a first pre-alloyed steel powder having a composition comprising in weight %: C 0.5-2, Cr 3.5-6, (2 Mo+W) 12-22, V 0.5-5, Co 0-12, Mn 0.1-0.5, Si 0.1-0.6, Fe balance apart from incidental impurities; providing a second pre-alloyed steel powder having a composition comprising in weight %: C 0.3-0.7, Cr 3-5.5, Mo 1-2.5, V 0.3-1.5, W 0-2, Mn 0.1-0.6, Si 0.8-1.2. Fe balance apart from incidental impurities; mixing together from 2 to 50 weight % of the first pre-alloyed steel powder with 98 to 50 weight % of the second pre-alloyed steel powder optionally up to 60 weight % of an iron powder and with carbon powder such that the final carbon content of the matrix of the sintered steel powder is a maximum of 1.1 weight %1; compacting the mixture and sintering to form the sintered steel.

Abstract: The method comprises preparing an iron-based powder mixture, and compressing and sintering the mixture to form the component. Said mixture comprises a first powder which forms 40 to 60 wt % of the mixture and which is an atomised pre-alloy comprising nickel, cobalt and iron, a second powder which forms 30 to 50 wt % of the mixture and essentially consists of iron, a third powder which essentially consists of ferromolybdenum, a fourth powder which essentially consists of graphite, and optionally a fifth powder which consists essentially of ferrotungsten. The component has a composition comprising 5 to 11 wt % of nickel, 5 to 11 wt % of cobalt, 5 to 8 wt % molybdenum, up to 1 wt % tungsten, 0.25 to 0.9 wt % carbon, and a balance which essentially consists of iron.

Abstract: An iron-based powder which is a mixture comprising a major proportion of a first alloy powder, a minor proportion of a second alloy powder and a proportion of a solid lubricant. The first alloy powder consists of, in weight percentages, 14 to 30 chromium, 1 to 5 molybdenum, 0 to 5 vanadium, 0 to 6 tungsten, the total of molybdenum, vanadium and tungsten being at least 3, a total of 0 to 5 of other strong carbide forming elements, 0 to 1.5 silicon, carbon with a minimum level sufficient to form carbides with substantially all of the molybdenum, vanadium, tungsten, and any other strong carbide forming elements present, and a balance which is iron and incidental impurities. The second alloy powder is an austenitic stainless steel.