TEMPERATURE DEPENDENCE OF HARDNESS OF L12 ORDERED ALLOYS.

Abstract

Hot hardness measurements were made on more than thirty polycrystalline binary L1//2 compounds to answer the question as to why only a limited number of L1//2 alloys show a positive temperature dependence of strength. Eleven alloys, Fe//3Ga, Pt//3In, Pt//3Sn, Pd//3Pb, Zr//3In, Pt//3V, Pt//3Cr, Pt//3Mn, Pd//3Mn, Pt//3Ti and Pd//4Ti, exhibited the strength anomaly, in addition to the alloys Ni//3Al, Ni//3Si, Ni//3Ga, Ni//3Ge, Zr//3Al and Co//3Ti which are already known. It was concluded that an L1//2 compound having a strength anomaly has a relatively low phase stability with respect to the DO//1//9, or most likely the DO//2//2 structure. This is consistent with the Kear-Wilsdorf mechanism.