【摘要】 采用光学显微镜、扫描电镜、显微维氏硬度计和拉伸试验机等研究了铸态VW54镁合金及其挤压态线材及退火态线材的显微组织和力学性能。结果表明：固溶处理使铸态VW54镁合金组织中晶界处分布的Mg₂₄（Gd, Y）₅相全部回溶，仅保留部分GdH₂稀土氢化物；热挤压后，线材发生了动态再结晶（DRX）,晶粒尺寸显著细化，形成了以第二相流线为间隔的粗细等轴晶混合的双峰晶粒结构；在300℃低温退火时，第二相流线处会发生二次析出，形成短棒状或点状的第二相；而在400℃和500℃较高温度退火时，流线状分布的第二相会发生不同程度的回溶；挤压态样品具有（0001）//ED的基面织构，经过300℃×2 h和400℃×2 h退火后，再结晶使组织的织构取向趋于随机，而500℃×2 h退火后的合金线材则形成了典型的稀土织构；挤压态样品的屈服强度、抗拉强度和伸长率分别为169 MPa、255 MPa和17.5%,经300℃×0.5 h退火后，分别为148 MPa、253 MPa和20.3%,经400℃×0.5 h退火后，则分别为153 MPa、244 MPa和16.4%。更多还原

【Abstract】 Microstructure and mechanical properties of as cast VW54 magnesium alloy and its extruded and annealed wires were studied by means of optical microscope, scanning electron microscopy, micro Vickers hardness tester and tensile testing machine. The results show that the Mg₂₄（Gd, Y）₅ phase distributed at the grain boundaries of the as-cast VW54 magnesium alloy is completely re dissolved by solution treatment, and only part of GdH₂ rare earth hydrides are retained. After hot extrusion, dynamic recrystallization（DRX） occurs in the wires, and the grain size is significantly refined, forming a bimodal grain structure with coarse and fine equiaxed grains separated by the second-phase flow lines. During low-temperature annealing at 300 ℃, secondary precipitation will occur at the second-phase flow lines, forming short rod-like or dot-like second phases. However, when annealed at higher temperatures of 400 ℃ and 500 ℃, the second phases distributed along the flow lines will be dissolved in varying degrees. The extruded sample has（0001）//ED basal texture. After annealing at 300 ℃ for 2 h and at 400 ℃ for 2 h, the recrystallization makes the texture orientation tend to be random, while the alloy wire after annealing at 500 ℃ for 2 h forms a typical rare earth texture. The yield strength, tensile strength and elongation of the extruded sample are 169 MPa, 255 MPa and 17.5%, respectively, and those of the sample annealed at 300 ℃ for 0.5 h are 148 MPa, 253 MPa and 20.3% respectively, while those of the sample annealed at 400 ℃ for 0.5 h are 153 MPa, 244 MPa and 16.4% respectively.更多还原