本文選題：Cu-Cr-Zr-Mg合金　切入點(diǎn)：析出貫序　出處：《南昌大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：本文對(duì)Cu-Cr-Zr-Mg合金的早期時(shí)效析出貫序以及合金的相變動(dòng)力學(xué)進(jìn)行了研究。利用透射電鏡、三維原子探針等微觀分析手段對(duì)Cu-Cr-Zr-Mg合金析出貫序、位向關(guān)系、微結(jié)構(gòu)(溶質(zhì)原子團(tuán)簇、納米結(jié)構(gòu)等)及其化學(xué)成分進(jìn)行了系統(tǒng)的研究,研究結(jié)果如下:(1)Cu-Cr-Zr-Mg合金450℃時(shí)效時(shí),時(shí)效的初期合金的硬度增長(zhǎng)迅速,在450℃時(shí)效4 h以后析出速率變緩。隨著時(shí)效時(shí)間的延長(zhǎng)硬度增長(zhǎng)速率逐漸變慢,2 h以后基本達(dá)到平衡。電導(dǎo)率增長(zhǎng)規(guī)律和硬度相似,從開始的51.3%IACS 5 min后增長(zhǎng)到65.5%IACS,2 h后達(dá)到83.2%IACS隨后電導(dǎo)率增長(zhǎng)緩慢。(2)Cu-Cr-Zr-Mg合金在450℃早期時(shí)效階段的析出貫序?yàn)?過飽和固溶體→GP zone(I)(fcc富Cr相)→GP zone(II)(有序fcc富Cr相)→有序bcc富Cr相(Heusler結(jié)構(gòu))時(shí)效過程中,在550℃下分解的順序是:過飽和固溶體→有序fcc富Cr相→有序bcc富Cr相。伴隨析出過程,析出相和基體的界面由完全共格界面向共格-半共格界面轉(zhuǎn)變,位向關(guān)系由cube-on-cube向N-W位向關(guān)系轉(zhuǎn)變。(3)合金在450℃時(shí)效5 min后出現(xiàn)一些松散的Cr溶質(zhì)原子富集區(qū),合金時(shí)效時(shí)間延長(zhǎng)到4 h時(shí)出現(xiàn)大量高密度的Cr溶質(zhì)原子團(tuán)簇現(xiàn)象。且隨著時(shí)效的進(jìn)行,Cr的分配系數(shù)增加。與此同時(shí),Zr,Fe,Mg和Si的分配系數(shù)減少。(4)Cu-Cr-Zr-Mg在450~550℃合金在不同溫度時(shí)效時(shí)的相變動(dòng)力學(xué)“S”曲線能很好的反應(yīng)出時(shí)效轉(zhuǎn)變的速率。從而可以運(yùn)用相變動(dòng)力學(xué)方程很好的描述析出過程。利用固溶態(tài)脫溶分解反應(yīng)機(jī)理的積分方程驗(yàn)證Avrami經(jīng)驗(yàn)方程描述該合金析出過程的正確性,從而揭示出合金在450~550℃時(shí)效時(shí)的反應(yīng)機(jī)理是三維擴(kuò)散控制。
[Abstract]:In this paper, the early aging precipitation sequence of Cu-Cr-Zr-Mg alloy and the phase transformation kinetics of the alloy have been studied. The precipitation sequence, potential relationship, microstructure (solute atom cluster) of Cu-Cr-Zr-Mg alloy have been studied by means of transmission electron microscope (TEM) and three-dimensional atomic probe. Nanostructures, etc.) and their chemical compositions were systematically studied. The results are as follows: the hardness of Cu-Cr-Zr-Mg alloy at 450 鈩，

本文編號(hào)：1599287