Effect of mold temperature on microstructure and mechanical properties of rheo-squeeze casting Mg--3Nd--0.2Zn--0.4Zr alloy.

The effect of mold temperature on microstructure and mechanical properties of a rheo-squeeze casting (RSC) Mg--3Nd--0.2Zn--0.4Zr (NZ30K) alloy were investigated. The results indicated that the rise of mold temperature contributed to the increase of particle size and alloy density and the decrease of dislocation density. The rapid coarsening and then the normal growth of the particles during solution treatment were observed, and the long-rod-like Zn₂Zr₃ phase occurred. After age treatment, rod-like b9 precipitate was found in the conventional squeeze casting (CSC) alloy, while two types of precipitates including b9 phase and small plate-like b0 phase were observed in the RSC alloy. The amount of Zn₂Zr₃ phase was increased with rising mold temperature. Compared with the T6-treated CSC sample, the T6-treated RSC sample presented higher mechanical properties due to the larger precipitation strengthening contribution, and the yield strength, ultimate tensile strength, and elongation were up to 160 MPa, 296 MPa, and 7.7%. [ABSTRACT FROM AUTHOR]