Abstract: An alloy made of heat treated material represented by Gd5(SixGe1?x)4 where 0.47?x?0.56 that exhibits a magnetic entropy change (??Sm) of at least 16 J/kg K, a magnetostriction of at least 2000 parts per million, and a magnetoresistance of at least 5 percent at a temperature of about 300K and below, and method of heat treating the material between 800 to 1600 degrees C. for a time to this end.

Abstract: An alloy made of heat treated material represented by Gd5(SixGe1−x)4 where 0.47≦x≦0.56 that exhibits a magnetic entropy change (−&Dgr;Sm) of at least 16 J/kg K, a magnetostriction of at least 2000 parts per million, and a magnetoresistance of at least 5 percent at a temperature of about 300K and below, and method of heat treating the material between 800 to 1600 degrees C. for a time to this end.

Abstract: Method of making an active magnetic refrigerant represented by Gd5(SixGe1−x)4 alloy for 0≦x≦1.0 comprising placing amounts of the commercially pure Gd, Si, and Ge charge components in a crucible, heating the charge contents under subambient pressure to a melting temperature of the alloy for a time sufficient to homogenize the alloy and oxidize carbon with oxygen present in the Gd charge component to reduce carbon, rapidly solidifying the alloy in the crucible, and heat treating the solidified alloy at a temperature below the melting temperature for a time effective to homogenize a microstructure of the solidified material, and then cooling sufficiently fast to prevent the eutectoid decomposition and improve magnetocaloric and/or the magnetostrictive and/or the magnetoresistive properties thereof.

Abstract: A cryocooler with a regenerator comprising one or more regenerator components, which are ductile and oxidation resistant, including a rare earth metal, an alloy of two or more rare earth metals, an alloy of a rare earth metal with a non-rare earth metal, and an alloy of a rare earth metal with at least one interstitial element.