Microstructures of the pulsed laser welded TiZrBeCuMo composite amorphous alloy joint

Amorphous alloys have great potential in industrial applications. However, metallurgical characteristics of those materials during laser welding are still unclear. In this research, pulsed Nd:YAG laser welding was performed on the β-Ti dendrite reinforced amorphous alloy plates. The microstructures of the welding joints were specially observed and analyzed. Results show that no metallurgical defects were found in the joints. There is no obvious heat affected zone between the fusion zone and base material. The microstructure in the fusion zone (FZ) consists of β-Ti grains and amorphous matrix. Due to the fast cooling speed and the shock effect from the laser pulse during welding, the spherical shape β-Ti grains in the FZ are in nanometer scales, which are much smaller than the dendrite β-Ti grains in the base materials (BM). Element distribution analysis showed that the Mo atoms trend to enter the β-Ti lattice to form a solid solution. Therefore, the Mo element has the similar distribution with the Ti element in the joint. The hardness in FZ is higher than that in BM.