原位生成铝基复合材料的激光焊接

Laser welding of in-situ particulate reinforced aluminum matrix composites

采用大功率激光器研究新型铝基复合材料TiB2/ZL101的焊接性能,TiB2粒子的存在增加了焊缝熔池粘度降低了熔池流动性,影响了焊缝成形,增加了气孔敏感性.焊缝中气孔主要来源于氢和复合材料中的残留盐.激光焊接过程中较大的冷却速度使得焊缝晶粒非常细小,TiB2粒子在焊缝中分布更均匀,没有出现粒子偏析,主要是因为TiB2粒子是属于纳米级,在凝固过程中被凝固界面前沿所捕获而没有被推移.TiB2粒子没有与铝基体发生界面反应生成脆性相Al3Ti及AlB2,TiB2粒子与Al基体界面结合较好.结果表明,激光焊接后没有破坏TiB2粒子的增强效果.

The weldability of in-situ TiB2 particulate reinforced ZL101 Al metal matrix composites by high power laser welding was studied. The studied results show that TiB2 particles increase the viscosity and decrease the fluidity of molten pool, so the sensitivity of porosity is improved and at the same time weld appearance becomes bad. The hydrogen porosity as mainly pores distributes at the bottom of molten pool and around the fusion line. The grains of weld seam are much finer than that of base metal because of higher cooling rate. There is no segregation and TiB2 particles distribute homogeneously in the weld seam because nanometer TiB2 particles are not removed but trapped by the solid-liquid interface during the process of solidification. According to the results of X-ray diffraction and TEM, there are no interface reaction products such as brittle Al3Ti or AlB2 between the matrix and TiB2 particles. The interface between TiB2 and Al matrix is smooth and the reinforcing effect of TiB2 is still unchanged.