STRUCTURE AND PROPERTIES OF CU2MNAL SYNTHESIZED BY MECHANICAL ALLOYING

The ferromagnetic Cu2MnAl Heusler alloy has been prepared via a combin ation of mechanical alloying and heat treatment. The metastable Cu2MnA l phase can be formed directly when Cu, Mn and Al powders are mechanic ally alloyed. The resulting single-phase nanocrystalline material is h ighly disordered. When heat treated at 473 K, the Heusler phase can be ordered. The saturation magnetization is then approximately half the value achieved in highly ordered alloys, prepared via conventional mel ting and casting techniques. When heat treated at 973 K, the magnetic properties of the resulting material are similar to those of previous reports. The Cu2MnAl phase can be disordered by mechanical milling, re sulting in a decrease in saturation magnetization and increase in coer civity. The Heusler phase has been found to be unstable when mechanica lly milled over extended periods.