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Al-Zn共析合金是一种典型的超塑性金属材料,其细小晶粒组织一般通过热处理获得。近来,热力学控制过程已经运用于微观组织细化。据此,将20 mm厚的铸锭分别按以下3种方案进行均匀化,并热轧至2 mm厚以获得细化微观组织。这3种方案分别为:1)均匀化后空冷和热轧;2)均匀化后水淬和热轧;3)均匀化后立即热轧。微观组织观察表明:采用方案1和3均匀化后形成片层组织,并且在热轧进行的时候破碎成细小的晶粒组织。采用方案2处理时,细小的晶粒组织直接通过热轧过程获得,中间没有形成层片组织。结果表明,采用方案3处理后获得的材料晶粒最小,其尺寸为1.6μm;室温下拉伸测试结果表明,采用方案3处理的材料的伸长率最大。
Al-Zn eutectoid alloy is a typical superplastic metal material, the fine grain structure is generally obtained by heat treatment. Recently, the thermodynamic control process has been applied to the microstructure refinement. Accordingly, the 20 mm-thick ingots were respectively homogenized according to the following three schemes and hot-rolled to 2 mm thick to obtain the refined microstructure. The three options are: 1) air cooling and hot rolling after homogenization; 2) water quenching and hot rolling after homogenization; and 3) hot rolling immediately after homogenization. Microstructure observation showed that the lamellar structure was formed after homogenization with schemes 1 and 3, and crushed into fine grains when the hot rolling was carried out. When using the scheme 2, the fine grain structure is directly obtained through the hot rolling process, and no lamellar structure is formed in the middle. The results show that the material obtained after the treatment of Scheme 3 has the smallest grain size of 1.6 μm. The tensile test results at room temperature show that the material treated with Scheme 3 has the highest elongation.