The enhancement of solid solubility limits of AlCo intermetallic compound by high-energy ball milling

Abstract

In this work the AlCo intermetallic compound has been prepared by high-energy ball milling of Co and Al powder mixtures with the composition of Co-50 at.% Al, Co-71.4 at.% Al, Co-76.5 at.% Al, and Co-81.8 at.% Al, respectively. X-ray diffraction and transmission electron microscopy analysis of powders milled for different times proved that the AlCo phase formed directly during milling of the powder mixture of the former three compositions. In the Co-81.8 at.% Al powder mixture the amorphous phase was first formed and then crystallized to the AlCo phase. The result of energy dispersion x ray showed that the composition of AlCo phase formed during milling of the above four compositions is in agreement with that of the powder mixture, although their crystal structure is that of the AlCo intermetallic compound. The results indicate that the solubility range of intermetallic compound during mechanical alloying processes can be greatly enhanced by high-energy ball milling. The enhancement of solubility is discussed based on the structural features of nanocrystals.