(1. 慈溪汇丽机电有限公司，慈溪 315333； 2. 慈溪阿尔特新材料有限公司，慈溪 315301； 3. 北京科技大学 材料科学与工程学院，北京 100083)
摘 要: 采用旋转永磁体搅拌工艺制备半固态A356铝合金浆料并进行流变压铸，研究热处理工艺对流变压铸样件本体力学性能的影响，并采用扫描电镜(SEM)和能谱分析仪(EDS)进行显微组织分析。结果表明：采用T51热处理时，当人工时效时间为3 h时，σb=290 MPa、δ=8.5%，此时δ达到最大值；延长人工时效时间，σb缓慢提高，但是δ下降；采用T6热处理时，当人工时效时间为1 h，σb=310 MPa、δ=16.5%；当人工时效时间4.5 h时，σb=335 MPa、δ=10.5%，此时σb达到最大值，δ达到最小值。T6热处理后，当人工时效时间为1 h，试样断口具有大量的撕裂棱和韧窝，在晶界处产生大量富Si的鹅卵石形状的强化相，当量直径小于4 μm。同时，在α(Al)基体内形成大量富Si和富Mg的GP区和亚稳相，还产生大量直径小于1 μm的Al、Si和Mg的氧化物，并钉扎在α(Al)基体内，与GP区和亚稳相共同对α(Al)基体起强化作用。
关键字: A356铝合金；力学性能；显微组织；热处理；流变压铸
（1. Cixi Huili Machinery and Electric Co., Ltd., Cixi 315333, China; 2. Cixi ALT advanced material Co., Ltd., Cixi 315301, China; 3. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China）
Abstract:Semisolid A356 aluminum alloy slurry was prepared and rheo-diecasted by rotating permanent magnet stirring process. The effect of heat treatment process on the mechanical properties of rheo-diecasting samples was studied, and microstructure of the samples was analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that when T51 heat treatment is used, after being artificially aged for 3 h, σb is 290 MPa, δ is 8.5%, at this time, δ value reaches the maximum. When artificial aging time is prolonged, σb value increases slowly, whereas δ value decreases. When T6 heat treatment is used, after being artificially aged for 1 h, σb=310 MPa, δ=16.5%. After being artificial aged for 4.5 h, σb=335 MPa, δ=10.5%, at this time, σb value reaches the maximum, whereas δ value reaches the minimum. After T6 heat treatment, and being artificially aged for 1 h, a large number of torn edges and dimples are produced on the sample fracture surface, and a large number of pebble-shape strengthening phases with rich Si are produced at the grain boundaries, whose equivalent diameter is within 4 μm. At the same time, substantial GP zones with rich Si and rich Mg and metastable phases form in α(Al) matrix, and a large number of Al, Si and Mg oxides with diameter less than 1 μm are produced and pinned in α(Al) matrix. These oxides play an important role in strengthening the α(Al) matrix with the GP zones and metastable phases.
Key words: A356 aluminum alloy; mechanical property; microstructure; heat treatment; rheo-diecasting
