论文部分内容阅读
采用以5 kW CO_2激光器为光源的激光立体成形(LSF)系统制备了两种成分的Ti_2 AlNb基合金,借助金相显微镜(OM)、扫描电子显微镜(SEM)、能谱分析(EDS)、X射线衍射(XRD)方法及显微硬度测试,对合金的组织形貌、相组成以及硬度进行了分析。结果表明,原子数分数为Ti-20%Al-27%Nb(以下简称A_1)时,沉积态合金的显微组织和相组成沿沉积方向呈现出B2(固溶体)→B2+O(魏氏组织)→B2(固溶体)的变化特征;原子数分数为Ti-22%Al-27%Nb(以下简称A_2)时,沉积态合金由枝晶β(Ti_(Nb))和枝晶间的B2+O两相组成。在沿沉积高度增加方向上枝晶一次臂长度变化比较明显,从试样底部的25μm左右变化到试样顶部的80μm左右。A_1合金的显微硬度从试样底部至顶部呈现低→高→低的变化趋势;A_2合金整体的显微硬度变化不大。
Two kinds of Ti 2 AlNb based alloys were prepared by laser solid state forming (LSF) system with a 5 kW CO 2 laser as a light source. The microstructures of Ti 2 AlNb based alloys were characterized by OM, SEM, EDS, Ray diffraction (XRD) method and microhardness test. The microstructure, phase composition and hardness of the alloy were analyzed. The results show that the microstructures and phase compositions of the as-deposited alloys exhibit the following relationships: B2 (solid solution) → B2 + O (Widmanstatten) in the deposition direction when the atomic fraction is Ti-20% Al-27% ) → B2 (solid solution). When the atomic fraction is Ti-22% Al-27% Nb (hereinafter referred to as A_2), the as-deposited alloy is composed of dendrite β (Ti_ (Nb) Phase composition. The length of dendrite primary arm changed obviously along the direction of increasing deposition height from about 25μm at the bottom of the sample to about 80μm at the top of the sample. The microhardness of A_1 alloy shows a trend of low → high → low from the bottom to the top of the sample. The microhardness of A_2 alloy does not change much.