Microstructure and mechanical properties of the as-cast and warm rolled Mg-9Li-x(Al-Si)-yTi alloys with x=1, 3, 5 and y=0.05 wt.%

The as-cast Mg-9Li alloys with difference Al-Si addition were fabricated using induction casting method under the argon atmosphere and then warm rolling process was performed at 473 K. The Al-Si addition to Mg-9Li alloy leads to the formation of Mg2Si intermetallic compounds and microstructural evolutions such as increased volume fraction of alpha-Mg phases and changed morphology of alpha-Mg primary phase on the as-cast specimens. Moreover, the addition of 0.05 wt.% Ti elements on Mg-9Li-3(Al-Si) alloy raised the further microstructural evolutions, e.g. volume fraction of alpha-Mg phases, which bring about change in the microstructure after warm rolling process. The effects of this micro alloying influences the formation of fine microstructure after warm rolling process, which is the main factor in determining the mechanical properties. With these microstructural evolutions, tensile strength was increased from 101.71 MPa to 247.41 MPa by the minor alloying and warm rolling process. Moreover, the remarkably enhanced strength of Mg-9Li-3(Al-Si) alloy was the results of the addition of 0.05 wt.% Ti from 247 MPa to 412 MPa. Furthermore, the warm press-forming tests were carried out at 523 K to evaluate the applicability of this novel alloy for commercial products. (C) 2017 Elsevier B.V. All rights reserved.