Crystallization behavior of heat-affected zone by laser remelting bulk metallic glass Zr₅₅Al₁₀Ni₅Cu₃₀

The microstructure evolution of bulk metallic glass Zr₅₅Al₁₀Ni₅Cu₃₀ during pulsed laser remelting is investigated. It is found that the remelted zone always keeps amorphous structure and the crystallization tendency in heat-affected zone (HAZ) increases with the laser energy density increasing or the scanning velocity decreasing. The crystallization in the HAZ can be avoided but the structural relaxation occurres when the scanning velocity is equal to or greater than 15 mm/s. When the crystallization occurres in the HAZ, the micron-scale spherical grain is formed in the pattern of the multi-layer with the inner coupled lamellar structure, and crystalline phases are composed of tetragonal Zr₂Cu and face-centered cubic Zr₂Ni. Crystallization in the HAZ near the bottom of molten pool is more severe than that in the region near edge of surface. The grain size in the HAZ near bottom of molten pool decreases away from the remelted zone, and the layer numbers of the spherical grain in the HAZ near the remelted zone are more than that near the substrate side.