Molybdenum (Mo) is of great potential in the nuclear energy field, however, the embrittlement and the lower tensile strength limit the application of the fusion welded joints. Titanium (Ti) and zirconium (Zr) were synchronously added into the fusion zone (FZ) to improve the tensile strength and certain ductility of laser beam welding joints. By utilizing high-resolution scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and nanoindentation, the microstructures and mechanical properties of FZs in the joints under different alloying strategies with Ti and Zr were analyzed. Zr is mainly present in Mo as Mo₂Zr, playing the second-phase strengthening effect; Ti is mainly present in Mo in an atomic state, playing a role of the solid - solution strengthening. The addition of Ti and Zr with different mass proportions can control the relative contents of Mo₂Zr phase and solid - solution atoms in the FZ, control the distribution of zigzag and flat grain boundaries and influence the relative distributions of low - angle grain boundaries (LAGBs) and high - angle grain boundaries (HAGBs). In the end, combined addition of Ti and Zr is possible to improve the tensile strength while decrease the loss of ductility of the joint.

钼（Mo）在核能领域具有巨大的潜力，但其脆化和较低的抗拉强度限制了熔焊接头的应用。在熔合区（FZ）中同步加入钛（Ti）和锆（Zr），以提高激光束焊接接头的抗拉强度和一定的延展性。利用高分辨率扫描电子显微镜 (SEM)、电子背散射衍射 (EBSD) 和纳米压痕，分析了 Ti 和 Zr 不同合金化策略下接头中 FZs 的显微组织和力学性能。Zr主要以Mo _{2 的形式}存在于Mo中Zr，起到二相强化作用；Ti主要以原子态存在于Mo中，起到固溶强化的作用。添加不同质量比例的Ti和Zr可以控制FZ中Mo ₂ Zr相和固溶原子的相对含量，控制锯齿状和平坦晶界的分布，影响小角度晶界的相对分布（ LAGBs) 和大角度晶界 (HAGBs)。最后，Ti和Zr的联合添加可以提高抗拉强度，同时减少接头的延展性损失。