(北京有色金属研究总院 有色金属材料制备加工国家重点实验室，北京 100088)
摘 要: 通过OM、SEM及布氏硬度分析，研究GWN751K镁合金在不同状态下的显微组织与性能，确定该合金的双级均匀化工艺参数。结果表明：合金经过440 ℃、6 h初级均匀化后，共晶组织开始发生分解，晶粒开始长大；经过535 ℃、16 h热处理后，合金晶粒明显长大，但元素分布 较为均匀，晶界处仅明显残留含Y化合物；均匀化处理使合金的力学性能得到改善，合金断裂强度为245 MPa，屈服强度为192 MPa，伸长率为12%，较铸态合金的力学性能均有所提高；合金变形抗力较铸态合金的有所增加，这种特性在450 ℃仍保留下来，但差别减小。
关键字: 稀土镁合金；均匀化；显微组织
（State Key Laboratory for Fabrication and Processing of Non-ferrous Metals,
Beijing General Research Institute for Non-ferrous Metals, Beijing 100088, China）
Abstract:The microstructures and properties of the as-cast and homogenized GWN751K magnesium alloy were investigated by optical microscopy, scanning electron microscopy and hardness measurement. The two-step homogenization parameters were determined. The results indicate that the eutectic structures in the as-cast alloy begin to decompose, and the grains begin to grow up after the alloy is homogenized at 440 ℃ for 6 h. After heat treatment at 535 ℃ for 16 h, the elements distribute uniformly and the grains grow up obviously, only yttrium element of intermetallic compounds leaves around boundary. The mechanical properties are improved after homogenization, with σb=245 MPa, σ0.2=192 MPa and δ=12%, which are better than those of the as-cast alloy. The flow stress of the homogenized alloy is higher than that of the as-cast alloy and this character is still retained until 450 ℃, but the difference decreases.
Key words: rare earth magnesium alloy; homogenization; microstructure
