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研究金属型铸造和消失模铸造Mg-10.1Gd-3.74Y-0.25Zr(质量分数,%)合金的组织结构和力学性能。结果表明:采用两种铸造工艺得到的合金具有相似的铸态组织,均由α-Mg固溶体相、α-Mg+Mg24(Gd,Y)5共晶相和立方状Mg5(Gd,Y)相组成;但金属型铸造合金的晶粒尺寸明显小于消失模铸造合金。经525°C,6h固溶处理后,合金中的共晶相完全溶入基体中,而立方状 Mg5(Gd,Y)相仍然存在。固溶处理后的合金在225 °C时效处理 4h后达到硬化峰值。经过时效处理后,消失模铸造合金和金属型铸造合金的室温抗拉强度分别提高到285MPa和325MPa,但两者的屈服强度相差不大。与金属型铸造相比,消失模铸造过程中合金的冷却速度相对较慢,而且消失模铸造Mg-Gd-Y-Zr合金铸件更容易产生缩松等铸造缺陷,这是造成两种合金强度差异的主要原因。
The microstructure and mechanical properties of Mg-10.1Gd-3.74Y-0.25Zr (mass fraction,%) alloy were investigated. The results show that the alloys obtained by the two casting processes have similar as-cast microstructure and consist of α-Mg solid solution, α-Mg + Mg24 (Gd, Y) 5 eutectic and cubic Mg5 (Gd, Y) However, the grain size of the metal casting alloy is obviously smaller than that of the lost foam casting alloy. After 525 ° C, 6h solution treatment, the eutectic phase in the alloy completely dissolved into the matrix, while the cubic Mg5 (Gd, Y) phase still exists. After solution treatment, the alloy reached the hardening peak after 4 h aging treatment at 225 ° C. After aging treatment, the room temperature tensile strength of the lost foam casting alloy and the metal casting alloy were increased to 285MPa and 325MPa, respectively, but the yield strengths of the two had little difference. Compared with metal casting, the cooling speed of the alloy during the lost foam casting is relatively slow, and the casting loss of the cast-Mg-Gd-Y-Zr alloy casting is more likely to cause casting defects such as shrinkage, which leads to the difference in strength between the two alloys The main reason.