Amorphization of Al-12at.%Ti–X(X=Cr, Fe, Ni, Cu) Mixed Powders by Mechanical Alloying

During mechanical alloying, MA, using a high energy planetary ball mill of Al-12at.%Ti–X (X=Cr, Fe, Ni, Cu) mixed powders, aluminum rich Al-(10∼15.8)at.%Ti-(3.4∼26.3)at.%X supersaturated solid solution with small grain sizes of 4∼6 nm are obtained. Increase in the concentration of the 3rd element Cr, Fe, Ni, promotes amorphization of the aluminum rich supersaturated solid solution by MA, though no amorphous phase is formed in Al-13.1at.%Ti mechanically alloyed powder. On the other hand, dissolution of about 12at.%Cu in Al-11at.%Ti supersaturated solid solution causes no amorphization during MA. The results obtained suggest that a critical value of the total elastic lattice strain, about 2% due to the largely, reduced lattice parameter in nano-size crystals is the most important factor for the amorphization of Al-rich supersaturated solid solutions.