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Indexed by:Journal Papers

Date of Publication:2019-09-01

Journal:CHINA FOUNDRY

Included Journals:SCIE

Volume:16

Issue:5

Page Number:319-325

ISSN No.:1672-6421

Key Words:AZ91; Sm; Ca; Si; grain refinement; mechanical properties; TG146; 22

Abstract:The effects of Sm, Si and Ca on the microstructure and mechanical property of AZ91 magnesium alloy were investigated by means of optical microscopy (OM), differential scanning calorimetry (DSC), scanning electronic microscopy (SEM), X-ray diffraction (XRD) and tensile testing. The results indicated that the addition of 1.5 wt.% Sm with or without 0.8 Si/Ca led to a decrease in the volume fraction of the beta-Mg17Al12 phase and the formation of the intermetallic compounds of Al-Sm, Mg2Si, MgAlCa and Al2Ca. The microstructure of AZ91 alloy was significantly refined and distribution became discrete with additions of Sm and Ca; the average grain size of the alpha-Mg matrix was reduced from 239.7 +/- 16.9 mu m to 66.34 +/- 5.10 mu m. The AZ91-Sm-Ca alloy exhibited a good combination of yield strength at 135 MPa, ultimate tensile strength at 199 MPa and elongation at 4.32%, which was ascribed to grain refinement strengthening. Furthermore, the T6 treated AZ91-Sm-Ca alloy possessed yield strength of 154 MPa and elongation of 7.1%, which was due to grain refinement strengthening and reduction in discontinuous precipitates.