Significant Mechanical Softening of an Al-Y-Ni-Co Metallic Glass on Cold and Hot Rolling

Deformation-induced crystallization behavior of the Al 85 Y 8 Ni 5 Co 2 metallic glassy samples subjected to cold and hot rolling with 35% size reduction is studied in the present work. The formation of primary nanoscale α-Al particles is observed after rolling at 473 K, which is below the glass-transition and crystallization temperature. It is found that contrary to thermal crystallization on heating below the glass-transition temperature, no intermetallic compounds but only α-Al nanoparticles were formed during the deformation-induced crystallization. The behavior is discussed in connection with the excess volume generated upon deformation. Structural changes are studied by x-ray diffractometry and transmission electron microscopy. Variation in the Vickers microhardness is also detected.