本文關(guān)鍵詞： Mg-0.3Zr合金 置換原子 原位金相 預(yù)變形 退火強(qiáng)化 形變孿晶　出處：《西安工業(yè)大學(xué)》2017年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：鎂合金以其優(yōu)異的綜合力學(xué)性能被稱(chēng)為“21世紀(jì)最具發(fā)展前途的綠色金屬結(jié)構(gòu)材料”,并已在航空航天、汽車(chē)、3C電子等領(lǐng)域得到了廣泛的應(yīng)用。但是目前普通應(yīng)用的鑄造鎂合金存在室溫強(qiáng)度和塑性低,高溫抗蠕變性能差等缺點(diǎn),制約了其在工業(yè)應(yīng)用上的進(jìn)一步拓展。因此提高鎂合金的室溫和高溫強(qiáng)度成了鎂合金研究中急需解決的首要問(wèn)題。本文首先以Mg-0.3Zr合金為主要研究對(duì)象,采用原位金相、透射電鏡、壓縮試驗(yàn)以及多向變形等手段研究了合金化元素Mn、Ag、Ca和Nd等對(duì)其退火強(qiáng)化效果的影響。其次,在此基礎(chǔ)上分析了不同Nd、Zr元素添加量對(duì)Mg-Nd-Zr合金顯微組織和變形行為的影響,最后得出如下結(jié)論:Mg-8.3Ag-0.3Zr、Mg-1Ca-0.3Zr、Mg-5.3Nd-0.3Zr合金最佳固溶處理工藝參數(shù)依次為450℃×7h、510℃×8h、550℃×9h。Mg-8.3Ag-0.3Zr、Mg-1Ca-0.3Zr、Mg-5.3Nd-0.3Zr合金鑄態(tài)組織的第二相分別為AgMg3、Mg2Ca和Mg12Nd。Mn、Ag元素對(duì)預(yù)變形Mg-0.3Zr合金沒(méi)有退火強(qiáng)化作用,而溶質(zhì)元素Ca和Nd對(duì)預(yù)變形Mg-0.3Zr合金具有退火強(qiáng)化作用,均可提高合金的壓縮強(qiáng)度。經(jīng)過(guò)150℃退火24小時(shí)處理后,Ca元素的退火強(qiáng)化作用最為明顯,增幅可達(dá)40MPa。溶質(zhì)元素Nd的最佳退火強(qiáng)化工藝為180℃保溫7小時(shí),1at%的Nd元素的強(qiáng)化效果可以達(dá)到76MPa。另外隨著Nd元素含量的增加,其退火強(qiáng)化效果先增加,后處于穩(wěn)定狀態(tài)。溶質(zhì)元素Nd經(jīng)過(guò)退火處理后會(huì)偏聚在Mg-Nd-0.3Zr合金預(yù)變形形成的孿晶界上,對(duì)形變孿晶產(chǎn)生釘扎作用,使得在進(jìn)一步變形中會(huì)產(chǎn)生新的大量孿晶而不是原有形變孿晶的長(zhǎng)大變寬,從而提高了合金的壓縮強(qiáng)度。隨著Mg-Nd-0.3Zr合金預(yù)變形量的增加,Nd元素的退火強(qiáng)化效果先增加后明顯減小,當(dāng)退火溫度達(dá)到210℃,則沒(méi)有強(qiáng)化效果。與室溫壓縮相比,高溫(150℃)慢速變形并不會(huì)改善Mg-Ca-0.3Zr合金的力學(xué)性能,而是當(dāng)變形速率超過(guò)0.01mm/min時(shí)會(huì)出現(xiàn)塑性失穩(wěn)現(xiàn)象。對(duì)Mg-5.3Nd-0.3Zr合金而言,高溫慢速變形可使其孿晶片層細(xì)化。另外隨著累積變形量的增加,合金中的形變孿晶密度增大,退火強(qiáng)化效果增強(qiáng)。
[Abstract]:Magnesium alloys with excellent comprehensive mechanical properties are known as "the most promising green metal structural materials in 21th century" and have been in aerospace, automotive. 3C electronics and other fields have been widely used, but the common casting magnesium alloy has the shortcomings of low room temperature strength and plasticity, poor creep resistance at high temperature and so on. Therefore, improving the strength of magnesium alloy at room and high temperature has become the most important problem in magnesium alloy research. Firstly, Mg-0.3Zr alloy is the main research in this paper. Object. In situ metallography, transmission electron microscopy, compression test and multidirectional deformation were used to study the effect of alloying elements MnAg-Ag-Ca and ND on the annealing strengthening effect. On the basis of this, the effect of different content of NdndlZr on the microstructure and deformation behavior of Mg-Nd-Zr alloy was analyzed. The conclusion is as follows: Mg-8.3Ag-0.3Zr. The optimum solution treatment parameters of Mg-1Ca-0.3Zr-Mg-5.3Nd-0.3Zr alloy are 450 鈩，

本文編號(hào)：1473065