(北京有色金屬研究總院 有色金屬材料制備加工國家重點實驗室，北京 100088)
摘 要: 通過OM、SEM及布氏硬度分析，研究GWN751K鎂合金在不同狀態(tài)下的顯微組織與性能，確定該合金的雙級均勻化工藝參數(shù)。結果表明：合金經(jīng)過440 ℃、6 h初級均勻化后，共晶組織開始發(fā)生分解，晶粒開始長大；經(jīng)過535 ℃、16 h熱處理后，合金晶粒明顯長大，但元素分布 較為均勻，晶界處僅明顯殘留含Y化合物；均勻化處理使合金的力學性能得到改善，合金斷裂強度為245 MPa，屈服強度為192 MPa，伸長率為12%，較鑄態(tài)合金的力學性能均有所提高；合金變形抗力較鑄態(tài)合金的有所增加，這種特性在450 ℃仍保留下來，但差別減小。
關鍵字: 稀土鎂合金；均勻化；顯微組織
（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
