(1. 廣州有色金屬研究院，廣州 510650；
2. 中南大學材料科學與工程學院，長沙 410083)
摘 要: 利用光學顯微鏡、掃描電子顯微鏡和X射線衍射儀分析鑄態(tài)和固溶態(tài)AZ91D-xSm(x=0~1)合金的組織和相組成，測試其室溫拉伸力學性能和沖擊韌性。結果表明：隨著Sm含量的增加，鑄態(tài)組織中不連續(xù)網狀β-Mg17Al12相發(fā)生破碎，數(shù)量逐漸減少，而小塊狀高熱穩(wěn)定性新相Al2Sm數(shù)量逐漸增多；拉伸力學性能和沖擊韌性整體均逐漸提高，AZ91D-0.88Sm合金的抗拉強度σb、伸長率δ和沖擊韌性αnK分別達到230 MPa、15.5%和24 J/cm2；經固溶處理后，β-Mg17Al12相完全固溶于α-Mg基體中，只存在Al2Sm相；拉伸力學性能和沖擊韌性均明顯提高，但其提高幅度隨著Sm含量的增加而有所減緩。
關鍵字: AZ91D合金；Sm變質；顯微組織；拉伸力學性能；沖擊韌性
（1. Guangzhou Research Institute of Non-ferrous Metals, Guangzhou 510650, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The microstructures and phase compositions of as-cast and solution-treatedAZ91D-xSm (x=0-1) alloys were investigated by optical microscopy, scanning electron microscopy andX-ray diffractometry. Meanwhile, the tensile mechanical property and impact toughness at ambient temperature were tested. The results show that the discontinuous networkβ-Mg17Al12phase breaks and decreases gradually among the as-cast microstructure with increasing the Sm content. Meanwhile, small block Al2Sm new phase with high thermal stabilityincreases gradually.The tensile mechanical property and impact toughness on the whole are enhanced gradually. Tensile strength σb, elongation δand impact toughness αnKof AZ91D-0.88Sm alloy reach230 MPa, 15.5% and 24 J/cm2, respectively. After solution treatment, β-Mg17Al12phase dissolves into α-Mg matrix completely and Al2Sm phase still exists. The tensile mechanical property and impact toughness are enhanced obviously and the improving amplitude decreases slightly with increasing the Sm content.
Key words: AZ91D alloy; Sm modification; microstructure; tensile mechanical property; impact toughness
