Ultrafine-grained Mg–9Li–1Zn alloy sheets exhibiting low temperature superplasticity

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2009-08, Vol.516 (1), p.17-22
• Main Authors: Kim, W.J., Kim, M.J., Wang, J.Y.
• Format: Article
• Language: English
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Deformation, plasticity, and creep; Elasticity. Plasticity; Exact sciences and technology; Fine grains; Magnesium alloys; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Physics; Rolling; Severe plastic deformation; Superplasticity; Treatment of materials and its effects on microstructure and properties
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2009.03.089

The microstructure and mechanical properties of the ultrafine grained Mg–9Li–1Zn (LZ91) alloy sheets prepared through HRDSR (high-speed-ratio differential speed rolling) process were examined. During HRDSR for a thickness reduction of 65% by a single pass at 398 K, the microstructure was significantly refined to grains with submicron size and the refined microstructure was homogeneous along thickness direction of a sheet. The HRDSRed alloy exhibited enhanced strength and ductility at room temperature, and excellent low temperature superplasticity in the temperature range 423–523 K (0.49–0.6 T m ). The superplastic elongations were comparable with those obtained by other severe-plastic-deformation techniques or even better. The superplastic deformation mechanism of the ultrafine grained LZ91 alloy in the temperature range between 423 and 523 K was found to be grain-boundary-diffusion controlled grain boundary sliding.