激光熔化沉积制造γ-TiAl合金的组织与性能

Microstructure and Properties of γ-TiAl Alloy Fabricated by Laser Metal Deposition

摘要:

通过激光熔化沉积制造技术成功制备了X×Y×Z（40 mm×5 mm×60 mm）的Ti-48Al-2Cr-2Nb合金沉积样品。利用光学显微镜（OM）、扫描电子显微镜（SEM）、X射线衍射（XRD）、透射电子显微镜（TEM）和背散射衍射（EBSD）分析了沉积样品的显微组织、相组成、晶粒取向及断口形貌；利用维氏硬度计测量了沉积样品不同位置上的硬度分布；利用拉伸机测量了沉积样品在Z向的拉伸性能。 结果表明，在最佳工艺参数条件下获得了成形良好的沉积样品，经过渗透检测后发现表面无裂纹。沉积样品的显微组织由γ+α2组成的层片状晶团及少量块状γ-TiAl相组成。在沉积状态下，沿试样Z方向的室温拉伸强度为425MPa，延伸率为3.3%。拉伸试样的断口形貌为准解理断口。

Abstract:

The deposited sample of x × y × z (40 mm × 5 mm × 60 mm) Ti-48Al-2Cr-2Nb alloy was successfully fabricated by laser metal deposition. The microstructure, phase composition, grain orientation and fracture morphology of the deposited sample were analyzed by optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM) and backscattering diffraction (EBSD). The hardness distribution at different positions of the deposited sample was measured by Vickers hardness tester. The tensile properties of the deposited sample in Z direction were measured by tensile machine. The results show that the well-formed deposited sample is obtained under the optimum process parameters, and no surface cracks are found after penetration detection. The microstructure of the deposited sample is composed of α2+γ lamellar colony and a small amount of bulk γ phase. For as-deposited γ-TiAl alloy, the room-temperature tensile strength along the Z direction is 425 MPa and the elongation is 3.3%. The fracture morphology of tensile specimen is quasi-cleavage fracture.