本文選題：Nd + 鎂合金��； 參考：《河南科技大學(xué)》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(xué)性及優(yōu)異的抗蠕變性能,廣泛應(yīng)用于汽車(chē)和航空航天工業(yè)中。近年來(lái)關(guān)于Mg-Gd-Y-Zr系耐熱鎂合金的研究日益增多,但其力學(xué)性能還有進(jìn)一步提升的潛力。本文以Mg-10Gd-3Y-0.5Zr合金為基礎(chǔ),加入不同含量(0、1wt.%、2wt.%、3wt.%、4wt.%)的Nd,研究Nd對(duì)合金顯微組織和力學(xué)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(qiáng)度,當(dāng)Nd添加量為2%時(shí),合金的抗拉強(qiáng)度和屈服強(qiáng)度達(dá)到最大值,分別為216MPa、209MPa,此時(shí)伸長(zhǎng)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(shí)效,隨著時(shí)效時(shí)間的增加,合金的布氏硬度值先增大后減小,在14h處達(dá)到峰值,因此最佳熱處理工藝確定為:固溶:535℃×6h;時(shí)效:225℃×14h。Nd的適量添加使時(shí)效態(tài)Mg-10Gd-3Y-xNd-0.5Zr系合金的低溫(室溫~200℃)力學(xué)性能略有降低,但提高了合金的高溫(250~350℃)力學(xué)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(qiáng)度和屈服強(qiáng)度先增大后減小,出現(xiàn)了強(qiáng)度反常溫度效應(yīng)。伸長(zhǎng)率隨Nd含量增多逐漸減小,隨拉伸溫度的升高逐漸增大。時(shí)效態(tài)Mg-10Gd3Y-xNd-0.5Zr系合金主要強(qiáng)化相為β"相、β'相及具有18R結(jié)構(gòu)的長(zhǎng)周期有序結(jié)構(gòu)(LPSO)相。時(shí)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(xué)性能。Mg-10Gd-3Y-2Nd-0.5Zr合金在200~300℃范圍下抗拉強(qiáng)度保持在280MPa以上,250℃為309.5MPa,特別是350℃拉伸時(shí)合金抗拉強(qiáng)度仍高達(dá)195MPa,表現(xiàn)出優(yōu)異的耐高溫性能,遠(yuǎn)超商用耐熱鎂合金WE54。時(shí)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(zhǎng)大。隨著蠕變溫度和應(yīng)力的升高,蠕變控制機(jī)制由擴(kuò)散及晶界滑動(dòng)機(jī)制逐漸向位錯(cuò)滑移、位錯(cuò)攀移機(jī)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(hào)：1731404