【摘要】：鎂合金作為一種輕質(zhì)的工程材料,越來越受到人們的關(guān)注和重視。目前,研究較為成熟且價格低廉的鎂合金的力學(xué)性能尤其高溫性能較差,這嚴重阻礙了鎂合金在汽車行業(yè)以及其他行業(yè)的應(yīng)用。而一些高溫性能比較好的鎂合金,大多是以稀土為主要添加元素的稀土鎂合金,而稀土高的價格同樣會限制稀土鎂合金的推廣和應(yīng)用。正是由于這種原因,國內(nèi)外開始關(guān)注成本低廉且又具有良好高溫性能的堿土鎂合金的研究和開發(fā)。目前,國內(nèi)外對于堿土鎂合金的研究大多集中在含Ca鎂合金上,而對于含Sr鎂合金的研究主要集中在Mg-Al-Sr基鎂合金上,對于其他含Sr新型堿土鎂合金的研究還非常少。因此,進一步針對含Sr新型堿土鎂合金的設(shè)計及其顯微組織和力學(xué)性能展開研究對于堿土鎂合金的發(fā)展以及加大鎂合金的推廣應(yīng)用具有非常重要的理論意義和實際意義。本文基于設(shè)計的Mg-3.5Sr-1Mn(wt%)新型含Sr堿土鎂合金作為研究對象,利用光學(xué)顯微鏡、DSC差熱分析儀、X射線衍射儀、掃描電鏡、拉伸試驗機和顯微硬度計等手段,研究了Ce、Sc和Nd合金化和/或微合金化及熱處理對Mg-3.5Sr-1Mn鎂合金顯微組織和力學(xué)性能的影響,并得到了以下主要研究結(jié)果:1)Mg-3.5Sr-1Mn試驗鎂合金的鑄態(tài)組織主要由α-Mg、α-Mn和Mg17Sr2三種相組成,并且合金經(jīng)T4處理(520℃×24 h+淬水)后,合金組織中的α-Mn和Mg17Sr2相仍然存在。此外,在Mg-3.5Sr-1Mn鎂合金中分別添加0.5-1.5 wt%Ce、0.15-0.45wt%Sc和0.5-1.5 wt%Nd后,合金鑄態(tài)組織和T4(520℃×24 h+淬水)熱處理組織中的合金相種類均沒有發(fā)生變化,但合金的鑄態(tài)晶粒被細化。2)在Mg-3.5Sr-1Mn試驗鎂合金中添加0.5-1.5 wt%Ce可以改善合金的室溫抗拉性能,并且隨著Ce添加量從0.5 wt%增加到1.5 wt%,含Ce合金的抗拉強度、屈服強度和延伸率均呈先下降然后上升的趨勢。在添加了0.5 wt%、1.0 wt%和1.5 wt%Ce的三個試驗合金中,以添加1.5 wt%Ce的合金具有相對較佳的室溫抗拉性能。此外,在Mg-3.5Sr-1Mn試驗鎂合金中添加0.5-1.5 wt%Ce對合金的斷裂方式?jīng)]有明顯影響,均呈典型的解理和/或準解理斷裂。3)在Mg-3.5Sr-1Mn試驗鎂合金中添加0.15-0.45 wt%Sc可使合金組織中第二相的分布更加均勻。同時,添加0.15-0.45 wt%Sc到Mg-3.5Sr-1Mn鎂合金中還可改善合金的室溫抗拉強度、屈服強度和延伸率,但隨著Sc添加量從0.15 wt%增加到0.45wt%,合金的抗拉強度和延伸率呈下降趨勢,而屈服強度卻稍有增加�？傮w而言,在添加了0.15 wt%、0.30 wt%和0.45 wt%Sc的三個試驗合金中,以添加0.15 wt%Sc的合金具有相對較佳的的室溫抗拉性能。此外,在Mg-3.5Sr-1Mn試驗鎂合金中添加0.15-0.45 wt%Sc對合金的斷裂方式?jīng)]有明顯影響,均呈典型的解理和/或準解理斷裂。4)在Mg-3.5Sr-1Mn試驗鎂合金中添加0.5-1.5 wt%Nd可使合金組織中第二相的分布更加分散。同時,添加0.5 wt%、1.0 wt%和1.5 wt%Nd對Mg-3.5Sr-1Mn合金的室溫抗拉性能存在不同的影響,其中0.5 wt%和1.0 wt%Nd可使合金的抗拉強度、屈服強度和延伸率增加,而添加1.5 wt%Nd后,雖然合金的延伸率增加但抗拉強度和屈服強度降低。在添加了0.5 wt%、1.0 wt%和1.5 wt%Nd的三個試驗合金中,以添加1.0 wt%Nd的合金具有相對較佳的室溫抗拉性能。此外,在Mg-3.5Sr-1Mn試驗鎂合金中添加0.5-1.5 wt%Nd對合金的斷裂方式?jīng)]有明顯影響,均呈典型的解理和/或準解理斷裂。
[Abstract]:Magnesium alloys, as a kind of lightweight engineering materials, have attracted more and more attention. At present, the mechanical properties of magnesium alloys with relatively mature and low price are especially poor at high temperature, which seriously hinders the application of magnesium alloys in automotive industry and other industries. Rare earth magnesium alloys with rare earth as the main additive element, and the high price of rare earth will also restrict the promotion and application of rare earth magnesium alloys. The research on Mg-Al-Sr-based magnesium alloys is mainly concentrated on Mg-Al-Sr-based magnesium alloys, while the research on other new alkaline-earth magnesium alloys containing Sr is very few. Therefore, further research on the design, microstructure and mechanical properties of new alkaline-earth magnesium alloys containing Sr is carried out to study the development and increase of alkaline-earth magnesium alloys. The popularization and application of magnesium alloys have very important theoretical and practical significance.Based on the new type of Mg-3.5Sr-1Mn(wt%) containing Sr alkaline soil magnesium alloys designed in this paper,the alloying of Ce,Sc and Nd was studied by means of optical microscope,DSC differential thermal analyzer,X-ray diffraction,scanning electron microscope,tensile tester and microhardness tester. The effects of and/or microalloying and heat treatment on the microstructure and mechanical properties of Mg-3.5Sr-1Mn magnesium alloys were investigated. The main results were as follows: 1) The as-cast microstructure of Mg-3.5Sr-1Mn alloy was mainly composed of three phases, namely, a-Mg, a-Mn and Mg17Sr2, and the microstructure of the alloy after T4 treatment (520 *24 H + quenching water). In addition, after adding 0.5-1.5 wt% Ce, 0.15-0.45 wt% Sc and 0.5-1.5 wt% Nd to Mg-3.5Sr-1Mn alloy respectively, the as-cast microstructure and T4 (520 *24 H + quenched water) heat treatment microstructure of the alloy have not changed, but the as-cast grains of the alloy have been refined.2) by adding 0.5-1.5 wt% in Mg-3.5Sr-1Mn test magnesium alloy. The tensile strength, yield strength and elongation of the alloys with Ce content increased from 0.5 wt% to 1.5 wt%. Among the three alloys with Ce content of 0.5 wt%, 1.0 wt% and 1.5 wt% Ce, the alloys with 1.5 wt% Ce have relatively better room temperature properties. In addition, the addition of 0.5-1.5 wt% Ce to M g-3.5Sr-1Mn alloy has no obvious effect on the fracture mode of the alloy, which is typical cleavage and/or quasi-cleavage fracture. 3) The addition of 0.15-0.45 wt% Sc to M g-3.5Sr-1Mn alloy can make the distribution of the second phase more uniform. The tensile strength, yield strength and elongation of the alloy at room temperature were also improved in g-3.5Sr-1Mn magnesium alloy. However, with the increase of Sc content from 0.15wt% to 0.45wt%, the tensile strength and elongation of the alloy decreased, while the yield strength increased slightly. In addition, the addition of 0.15-0.45 wt% Sc to Mg-3.5Sr-1Mn test magnesium alloy has no obvious effect on the fracture mode of the alloy, and both of them show typical cleavage and/or quasi-cleavage fracture. 4) Adding 0.5-1.5 wt% Nd to Mg-3.5Sr-1Mn test magnesium alloy can make the second-order fracture in the alloy structure. At the same time, the addition of 0.5 wt%, 1.0 wt% and 1.5 wt% Nd has different effects on the tensile properties of Mg-3.5 Sr-1Mn alloy at room temperature. Among them, 0.5 wt% and 1.0 wt% Nd can increase the tensile strength, yield strength and elongation of the alloy, while the addition of 1.5 wt% Nd can increase the elongation but decrease the tensile strength and yield strength. Among the three test alloys with 0.5 wt%, 1.0 wt% and 1.5 wt% Nd, the alloys with 1.0 wt% Nd have relatively better tensile properties at room temperature. In addition, the addition of 0.5-1.5 wt% Nd to Mg-3.5 Sr-1 Mn test magnesium alloys has no obvious effect on the fracture mode of the alloy, showing typical solution and / or quasi-solution fracture.
【學(xué)位授予單位】：重慶理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG146.22;TG166.4

【參考文獻】

相關(guān)期刊論文 前3條

1 呂渠東,呂宜振,曾小勤,丁文江,盧晨;鎂合金在電子器材殼體中的應(yīng)用[J];材料導(dǎo)報;2000年06期

2 趙浩峰;王玲;孫磊;章帥;顏開;李慶芳;劉孟寅;;鎂錳鍶合金力學(xué)性能的研究[J];材料研究與應(yīng)用;2009年04期

3 劉生發(fā);康柳根;韓輝;劉林艷;鄒曉強;郭洪河;;Influence of electromagnetic stirring on microstructure of AZ91-0.8%Ce magnesium alloy[J];Journal of Central South University of Technology(English Edition);2006年06期

，

本文編號：2205077