摘要
The effects of Al-8B grain refiner on microstructure and tensile properties of an Al-12Zn-3Mg-2.5Cu alloy produced by modified strain induced melt activation process were investigated. Pre-deformation of 60% was used by hot working at 300 ℃. After pre-deformation, the samples were heated to a temperature above the solidus and below the liquidus point and maintained in the isothermal conditions at three different temperatures（500, 550 and 590 ℃） for varying time（10, 20 and 40 min）. It was observed that strain induced melt activation has caused the globular morphology of α（Al） grains. Microstructural study was carried out on the alloy by using optical microscope and scanning electron microscope in both unrefined and B-refined conditions. The results showed that for the desired microstructures of the alloy during SIMA process, the optimum temperature and time are 550 ℃ and 10 min, respectively. After the T6 heat treatment, the average tensile strengths increased from 278 to 585 MPa and 252 to 560 MPa for samples refined with 3.75% Al-8B before and after SIMA process, respectively. The ultimate strength of SIMA specimens is lower than that of B-refined specimens.
研究Al-8B晶粒细化剂对应变诱导熔化激活法制备的Al-12Zn-3Mg-2.5Cu合金显微组织与力学性能的影响。并在300°C对合金进行预变形量为60%的热加工。预变形后,将合金加热至介于固相线和液相线的某一温度(500,550和590°C),并保温不同时间(10,20和40 min)。应变诱导熔化激活法可得到球状α(Al)晶粒。采用光学显微镜和扫描电子显微镜观察细化和未细化合金的显微组织。结果表明,应变诱导熔化激活制备过程中在550°C下保温10 min,可以得到满意的显微组织。经T6热处理后,采用3.75%Al-8B细化和应变诱导熔化激活法制备的合金的平均拉伸强度分别从278 MPa增加至585 MPa,252MPa增加至560 MPa。SIMA合金的抗拉强度比B细化合金的抗拉强度低。
