Microstructure Evolution and Mechanical Properties of Ti-25Ta Alloy Fabricated by Selective Laser Melting and Hot Isostatic Pressing

Ti-25Ta alloy samples were fabricated by selective laser melting,and the relative density,microstructure,microhardness and tensile properties of the as-built and hot isostatic pressing(HIP)-prepared samples were characterized.Results show that the track width and penetration depth are increased with the increase in laser power,and the surface morphology is improved.The maximum relative density improves from 95.31%to 98.01%after HIP process.Moreover,the microstructure is refined into the lath martensite and cellular grains with the increase in input power.After densification treatment,the subgrain coalescence occurs and high angle grain boundaries are formed.In addition,HIP process stabilizes the microhardness and enhances the tensile strength and elongation.

激光工艺参数对选区激光熔化钽微观组织和力学性能的影响

研究了单、双层扫描策略和能量密度(246~640 J/mm^(3))对选区激光熔化钽显微组织及力学性能的影响。采用扫描电子显微镜和电子背散射衍射对选区激光熔化钽的显微组织进行表征,并对其显微硬度和拉伸性能进行检测。结果表明,选区激光熔化钽显微组织由明显向上生长的柱状晶构成,双层扫描后的钽具有更细的晶粒尺寸。随着输入能量密度的提高,选区激光熔化钽的强度、显微硬度和塑性均具有明显的上升趋势。此外,双层扫描工艺可进一步提高材料密度,且在保留强度的基础上,增强材料塑性。在能量密度为640J/mm^(3)(双层扫描)时,金属钽性能最优,显微硬度、极限抗拉伸强度及延伸率分别为2307 MPa,527 MPa和11.4%。