选区激光熔化制备W-25%Re合金组织和性能研究

Research on Microstructure and Properties of W-25%Re Alloy Prepared by Selective Laser Melting

以球形W-25Re(质量分数,%,下同)合金粉末为原料,采用选区激光熔化(selective laser melting,SLM)技术制备W-25Re合金试样,研究工艺参数对W-25Re合金组织和性能的影响。利用分析天平、场发射扫描电镜、X射线衍射仪和显微硬度仪等分析方法表征SLM制备的W-25Re合金试样的相对密度、显微组织、相组成和显微维氏硬度等性能。结果表明:SLM制备W-25Re合金过程中无明显的球化、翘曲、变形、分层或不能成形现象,试样表面和侧面无明显孔洞和裂纹等缺陷,成形性良好。随着输入体能量密度逐渐增大,W-25Re合金试样内部垂直面晶粒形态逐渐从等轴晶和柱状晶混合转变为粗大的柱状晶。W-25Re合金试样仅含有立方晶系W_(13)Re_(7)相,衍射峰2θ角向左偏移的变化主要是由残余应力造成的。激光功率和扫描速度对W-25Re合金试样相对密度的影响显著。当体能量密度为1050 J/mm^(3),即激光功率210 W,扫描速度200 mm/s时,可获得相对密度高达98.493%的W-25Re合金试样;此时,试样水平面和垂直面的显微硬度(HV_(0.2))分别为5153.8和5101.9 MPa,与轧制态W-25Re合金硬度值接近。

The W-25Re alloy was prepared by selective laser melting(SLM)using spherical W-25Re(wt%)alloy powder as the raw material.The effects of process parameters on the microstructure and properties of W-25Re alloy were investigated.The relative density,microstructure,phase composition,and Vickers microhardness of W-25Re alloy were characterized by analytical balance,field emission scanning electron microscope,X-ray diffractometer and microhardness tester.The results show that there are no obvious spheroidization,warping,deformation,delamination or non-forming phenomena during the preparation of W-25Re alloy by SLM.No obvious defects such as holes and cracks appear on the surface and side of the samples,and the formability of W-25Re alloy is good.With the increase in volumetric energy density(Ev),the grain morphology in the vertical plane of W-25Re alloy samples gradually changes from the mixture of equiaxed and columnar grains to coarse columnar grains.W-25Re alloy samples only contain the cubic W_(13)Re_(7)phase,and the leftward shift of the diffraction peak 2θangle is mainly caused by residual stress during the forming process.The influence of laser power and scanning speed on the relative density of W-25Re alloy is significant.When Ev is 1050 J/mm^(3),that is,the laser power is 210 W and the scanning speed is 200 mm/s,the W-25Re alloy sample with a relative density up to 98.493%can be obtained,of which the microhardness(HV_(0.2))in the horizontal and the vertical planes is as high as 5153.8 and 5101.9 MPa,respectively,which are close to the hardness value of the rolled W-25Re alloy.