期刊
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
卷 528, 期 3, 页码 1149-1153出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.msea.2010.09.096
关键词
Equal-channel angular pressing (ECAP); Magnesium alloys; Bimodal; Severe plastic deformation; Superplasticity
The Mg-6Zn-2Al alloy was processed by ECAP and microstructure and mechanical properties of the alloy before and after ECAP were studied. The results revealed that the microstructure of the ZA62 alloy was successfully refined after two-step ECAP (2 passes at 473 K and 2-8 passes at 423K). The course bulk interphase of Mg(51)Zn(20) was crushed into fine particles and mixed with fine matrix grains forming stripes in the microstructure after the second step of ECAP extrusion. A bimodal microstructure of small grains of the matrix with size of similar to 0.5 mu m in the stripes and large grains of the matrix with size of similar to 2 mu m out of stripes was observed in the microstructure of samples after 4-8 passes of ECAP extrusion at the second step. The mechanical properties of the alloy studied were significantly improved after ECAP and the highest yield strength and elongation at room temperature were obtained at the samples after 4 and 8 ECAP passes at the second step, respectively. Tensile tests carried out at temperature of 473 K to 573 K and strain rate of 1 x 10(-3) s(-1) to 3 x 10(-2) s(-1) revealed that the alloy after 8 ECAP passes at the second step showed superplasticity and the highest elongation and strain rate sensitivity (m-value) reached 520% and 0.45, respectively. (C) 2010 Elsevier B.V. All rights reserved.
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