摘要
A new cast Mg-2Gd-2Nd-2Y-1Ho-1Er-0.5Zn-0.4Zr （wt%） alloy was prepared by direct-chill semicontinuous casting technology. The microstructure, mechanical properties and thermal conductivity of the alloy in as-cast, solid-solution treated and especially peak-aged conditions were investigated. The as-cast alloy mainly consists of α-Mg matrix, （Mg, Zn）3 RE phase and basal plane stacking faults. After proper solid-solution treatment, the microstructure becomes almost Mg-based single phase solid solution except just very few RE-riched particles. The as-cast and solid-solution treated alloys exhibit moderate tensile properties and thermal conductivity. It is noteworthy that the Mg alloy with 8 wt% multiple RE exhibits remarkable age-hardening response （AHV=35.7）, which demonstrates that the multiple RE （RE = Gd, Nd, Y, Ho, Er） alloying instead of single Gd can effectively improve the age-hardening response. The peak-aged alloy has a relatively good combination of high strength/hardness （UTS （ultimate tensile strength） 〉 300 MPa; TYS （tensile yield strength）〉210 MPa; 115.3 HV）, proper ductility （ε≈ 6%） and moderate thermal conductivity （52.5 W/（m K））. The relative mechanisms mainly involving aging precipitation of β″ and β＂ phases were discussed. The results provide a basis for development of high performance cast Mg alloys.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.
A new cast Mg-2Gd-2Nd-2Y-1Ho-1Er-0.5Zn-0.4Zr （wt%） alloy was prepared by direct-chill semicontinuous casting technology. The microstructure, mechanical properties and thermal conductivity of the alloy in as-cast, solid-solution treated and especially peak-aged conditions were investigated. The as-cast alloy mainly consists of α-Mg matrix, （Mg, Zn）3 RE phase and basal plane stacking faults. After proper solid-solution treatment, the microstructure becomes almost Mg-based single phase solid solution except just very few RE-riched particles. The as-cast and solid-solution treated alloys exhibit moderate tensile properties and thermal conductivity. It is noteworthy that the Mg alloy with 8 wt% multiple RE exhibits remarkable age-hardening response （AHV=35.7）, which demonstrates that the multiple RE （RE = Gd, Nd, Y, Ho, Er） alloying instead of single Gd can effectively improve the age-hardening response. The peak-aged alloy has a relatively good combination of high strength/hardness （UTS （ultimate tensile strength） 〉 300 MPa; TYS （tensile yield strength）〉210 MPa; 115.3 HV）, proper ductility （ε≈ 6%） and moderate thermal conductivity （52.5 W/（m K））. The relative mechanisms mainly involving aging precipitation of β″ and β＂ phases were discussed. The results provide a basis for development of high performance cast Mg alloys.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.
基金
supported by the Natural Science Foundation of Heilongjiang Province of China (No. E2017030)
National Natural Science Foundation of China (No. 51301048)
Foundation of State Key Laboratory of Rare Earth Resources Utilization (No. RERU2016025)
Central University Foundation of Harbin Engineering University (No. GK2100260207)
the Natural Science Foundation of Jiamusi University of China (No. JMSURCGG2016006)
