多路粉末送进激光立体成形钨合金组织凝固形态分析

钨合金因具有优异的高温性能和抗蠕变、辐射、耐磨等性能在核工业、电子、兵器工业中备受关注。采用多路粉末送进的激光立体成形方法在碳钢基体表面制备了不同组分的Wi-Ni合金材料,研究了激光工艺参数对单道单层和单道多层W-Ni合金的微观组织的影响,利用CA模型进行了W-Ni合金的枝晶生长模拟,利用能谱和SEM表征的W-Ni合金成分及微观组织进行了对比。结果表明:合适的激光立体成形(LSF)工艺参数下,通过多路元素混合可以形成不同组分的W-Ni合金,合金内部组织致密,主要由未完全溶化的钨颗粒,以及W-Ni、W-Ni-Fe的化合物组成;多层沉积后,合金形成了明显的分层结构,组织从底部W-Ni-Fe杂乱枝晶逐渐过渡到顶部W-Ni二元共存的形态;CA模型的计算表明,在熔池底部无法消除等轴晶带来的影响,与试验结果一致;W90%-Ni(质量分数)的强度达到了882 MPa。

Solidification Morphology Analysis of Tungsten Alloy by Laser Solid Forming with Multi-channel Powder Feeding

Tungsten alloys have attracted much attention in the nuclear, electronics and weapons industries due to their excellent high temperature properties, resistance to creep, radiation, and wear resistance. Wi-Ni alloys with different composition were prepared on the surface of carbon steel substrates using a laser solid forming (LSF) method with multi-channel powder feeding. The effect of laser process parameters on the microstructure of single layer and multilayer W-Ni alloys was studied. The dendritic growth simulation of W-Ni alloy were carried out by a CA model, and the composition and microstructure of the W-Ni alloys were compared with that characterized by EDS and SEM. Results show that W-Ni alloys with different composition can be formed by multiple elements mixing under appropriate LSF process parameters. The microstructure of the alloy is dense, composed mainly of the tungsten particles that are not completely dissolved, and the compounds of W-Ni and W-Fe. After multilayer deposition, the alloy has formed a distinct stratified structure. The microstructure is gradually transited from the bottom W-Ni-Fe disorder dendrites to the top W-Ni dual coexistence. CA model calculation shows that the influence of equiaxed crystals cannot be eliminated, and a messy equiaxed zone is formed at the bottom of the melting pool, which agrees with the experimental results. The tensile strength of the W90%-Ni is up to 882 MPa.