本文選題：Nd + 鎂合金��； 參考：《河南科技大學》2017年碩士論文

【摘要】：鎂-稀土系(Mg-RE)合金具有良好的室溫和高溫力學性及優(yōu)異的抗蠕變性能,廣泛應用于汽車和航空航天工業(yè)中。近年來關于Mg-Gd-Y-Zr系耐熱鎂合金的研究日益增多,但其力學性能還有進一步提升的潛力。本文以Mg-10Gd-3Y-0.5Zr合金為基礎,加入不同含量(0、1wt.%、2wt.%、3wt.%、4wt.%)的Nd,研究Nd對合金顯微組織和力學性能的影響。研究結(jié)果表明:鑄態(tài)Mg-10Gd-3Y-0.5Zr合金組織由α-Mg基體和Mg5(Gd,Y)相組成,添加Nd后出現(xiàn)了新相Mg41Nd5。加入適量Nd能改善合金組織,提高合金強度,當Nd添加量為2%時,合金的抗拉強度和屈服強度達到最大值,分別為216MPa、209MPa,此時伸長率為2.6%。鑄態(tài)Mg-10Gd-3Y-2Nd-0.5Zr合金經(jīng)固溶535℃×6h處理后,晶界上絕大部分析出相溶入基體,然后在225℃時效,隨著時效時間的增加,合金的布氏硬度值先增大后減小,在14h處達到峰值,因此最佳熱處理工藝確定為:固溶:535℃×6h;時效:225℃×14h。Nd的適量添加使時效態(tài)Mg-10Gd-3Y-xNd-0.5Zr系合金的低溫(室溫~200℃)力學性能略有降低,但提高了合金的高溫(250~350℃)力學性能。隨著Nd含量的增加,合金高溫耐熱性能逐漸升高;同種成分合金隨拉伸溫度的升高,抗拉強度和屈服強度先增大后減小,出現(xiàn)了強度反常溫度效應。伸長率隨Nd含量增多逐漸減小,隨拉伸溫度的升高逐漸增大。時效態(tài)Mg-10Gd3Y-xNd-0.5Zr系合金主要強化相為β"相、β'相及具有18R結(jié)構(gòu)的長周期有序結(jié)構(gòu)(LPSO)相。時效態(tài)Mg-10Gd-3Y-xNd-0.5Zr系合金具有優(yōu)異的室溫及高溫力學性能。Mg-10Gd-3Y-2Nd-0.5Zr合金在200~300℃范圍下抗拉強度保持在280MPa以上,250℃為309.5MPa,特別是350℃拉伸時合金抗拉強度仍高達195MPa,表現(xiàn)出優(yōu)異的耐高溫性能,遠超商用耐熱鎂合金WE54。時效態(tài)Mg-10Gd-3Y-2Nd-0.5Zr合金在(200℃、250℃、300℃)/(50MPa、70MPa、90MPa)下具有優(yōu)異的高溫抗蠕變性能,明顯優(yōu)于商用耐熱鎂合金WE54。250℃蠕變后β'相轉(zhuǎn)變成β相,300℃蠕變后β相明顯長大。隨著蠕變溫度和應力的升高,蠕變控制機制由擴散及晶界滑動機制逐漸向位錯滑移、位錯攀移機制轉(zhuǎn)變。
[Abstract]:Mg-RE-based magnesium-rare earth alloys have good mechanical properties at room and high temperatures and excellent creep resistance. They are widely used in automotive and aerospace industries.In recent years, the research of Mg-Gd-Y-Zr series heat resistant magnesium alloy is increasing day by day, but its mechanical properties still have the potential to improve further.Based on Mg-10Gd-3Y-0.5Zr alloy, the effect of ND on microstructure and mechanical properties of the alloy was studied by adding Nds with different content of 01wt. and 2wt.and 3wt.and 4wt.k.). The effect of ND on the microstructure and mechanical properties of the alloy was studied.The results show that the microstructure of as-cast Mg-10Gd-3Y-0.5Zr alloy is composed of 偽 -Mg matrix and Mg5 + GdGdY) phase, and a new phase Mg41Nd5 appears after addition of ND.The addition of proper amount of ND can improve the microstructure and strength of the alloy. When ND addition is 2, the tensile strength and yield strength of the alloy reach the maximum value, which is 216MPa and 209MPa, respectively, and the elongation of the alloy is 2.6%.After treated with solid solution at 535 鈩，

本文編號：1731404