Calculation of crystallization start line for Zr₄₈Cu₄₅Al₇ bulk metallic glass at a high heating and cooling rate

An effective method of obtaining the crystallization start (CS) line for bulk metallic glass (BMG) at a high heating and cooling rate, by which the required welding parameters can be estimated intuitively, has been studied. A fixed laser spot heat source, which can heat and cool BMG at a high rate, was used to re-melt Zr₄₈Cu₄₅Al₇ BMG. The analysis of crystallization characteristics in the heat-affected zone (HAZ) indicated that at the boundary between the HAZ and the parent alloy there exist a critical state between crystalline and amorphous. The CS line should be tangent with the thermal cycle at the boundary, and the tangential point is most likely to be the transition location of the heating and cooling section in the thermal cycle. Based on simulated thermal cycles at the boundaries with different re-melting conditions by the finite-element method, the CS line for Zr₄₈Cu₄₅Al₇ BMG at a high heating and cooling rate was constructed. Crown