Influence of glass forming ability of alloy on crystallization in heat-affected zone by laser remelting Zr based bulk metallic glasses

Crystallization in the heat-affected zone with nominal composition of Zr₅₅Al_l0Ni₅Cu₃₀ and Zr₆₅Al_7.5Ni₁₀Cu_17.5, which has different glass forming abilities, is investigated during pulsed Nd:YAG laser remelting processing. It is found that the crystallization in the heat-affected zone for Zr₆₅Al_7.5Ni₁₀Cu_17.5 alloy with low glass forming ability is more severe than that for Zr₅₅Al_l0Ni₅Cu₃₀ alloy. There are only small number of micron-scale spherical grains sparsely formed in heat-affected zone, even Zr₅₅Al_l0Ni₅Cu₃₀ alloy is laser remelted repeatedly by four times. However, the heat-affected zone is almost fully covered with the spherical grains when Zr₆₅Al_7.5Ni₁₀Cu_17.5 alloy is laser remelted once. When Zr₆₅Al_7.5Ni₁₀Cu_17.5 alloy is laser remelted by four times, the size of spherical grains increase obviously, and there exhibits a radial dendritic growth in the spherical grain. Crystallization in the heat-affected zone for bulk metallic glasses during pulsed Nd:YAG laser remelting mainly depends on the glass forming ability of the alloy, and the high glass-forming ability is in favor of keeping the heat-affected zone under amorphous state.