原位ZrB_(2p)/6061Al复合材料的大功率高速激光焊接成形和组织演变

Weld Formation and Microstructure Evolution of High Power and High-Speed Laser Welded In-situ ZrB_(2p)/6061Al Composites

通过原位合成法制备5%(质量分数)ZrB_(2p)/6061Al复合材料,并对其进行激光焊接组织和力学性能研究。XRD和EDS分析表明,通过Al-K_(2)ZrF_(6)-KBF_(4)原位反应体系成功制备5%ZrB_(2p)/6061Al复合材料。通过OM和SEM分析,与基体6061Al合金相比,ZrB_(2p)/6061Al复合材料中的纳米ZrB_(2)颗粒产生的异质形核和钉扎效应对基体晶粒具有一定的晶粒细化作用,但纳米级颗粒团簇体的存在使其细化效果受到局限。进行激光焊接试验,在保证完全焊透的情况下,采用3.6kW、2.4m/min的大功率高速焊接可获得成形良好的焊缝。激光快速熔凝过程使基体晶粒进一步高度细化,大量ZrB_(2)团簇体基本消失,ZrB_(2)颗粒基本均匀分散,通过电子显微镜研究ZrB_(2)颗粒的迁移行为,发现激光熔池的熔体搅动和快速凝固过程实现了ZrB_(2)颗粒的2次分布。焊缝组织的优化提高了焊接接头的维氏硬度和抗拉强度,分别最高达到561.54MPa和125.17MPa,并探讨了焊缝的强化机制。

The 5wt%Zr B_(2p)/6061Al composite was prepared by in-situ synthesis and the microstructure of laser welding and mechanical properties were studied.XRD and EDS analysis results show that 5wt%Zr B_(2p)/6061Al composites are successfully prepared by the Al-K_(2)Zr F_(6)-KBF_(4) in-situ reaction system.By OM and SEM analysis,compared with the matrix 6061Al alloy,the heterogeneous nucleation effect and pinning effect of the nano Zr B_(2) particles has a certain grain refinement effect on the matrix grains of the composite,but the existence of nanoparticle clusters makes the refinement effect limited.During laser welding,under the condition of complete penetration,a high-power and high-speed welding of 3.6 k W and 40 mm/s can be utilized to obtain a well-formed weld.The rapid laser melting process and solidification make the matrix grains further refined,a large number of Zr B_(2) clusters basically disappear,and Zr B_(2) particles are basically evenly dispersed.By analyzing the migration behavior of Zr B_(2) particles,it is found that the melt agitation and rapid solidification process of the laser molten pool achieve the twice distribution of Zr B_(2) particles.The optimization of the weld microstructure improves the Vickers hardness (HV) and the tensile strength of the welded joint,up to 561.54 MPa and 125.17 MPa,respectively.And the strengthening mechanism of weld was discussed.