Microstructure evolution and thixoextrusion of
AZ91D magnesium alloy produced by SSTT
AZ91D magnesium alloy produced by SSTT
(1. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China;
2. Southwest Technique and Engineering Institute, Chongqing 400039, China)
2. Southwest Technique and Engineering Institute, Chongqing 400039, China)
Abstract: The semi-solid thermal transformation (SSTT) route was used to obtain semi-solid billets for thixoextrusion. Microstructural evolution during partial remelting was studied. Mechanical properties of thixoextruded billets were determined. The results show that the solid grain size decreases initially and then increases as the isothermal holding time increases. Furthermore, shape factor measurements show that the solid grains tend to become increasingly spheroidal after 10 min isothermal holding. With longer isothermal holding time, the degree of spheroidization slightly decreases. Middle ultimate tensile strength (263.3 MPa) is obtained for thixoextruded AZ91D alloy produced by the SSTT route, with a yield strength of 120.0 MPa and an elongation to fracture of 7.19％.
Key words: AZ91D magnesium alloy; microstructure; semi-solid thermal transformation; thixoextrusion