【摘要】：鎂合金在電子通訊、汽車制造及航空航天等領(lǐng)域具有廣闊的應(yīng)用前景及發(fā)展?jié)摿?被譽(yù)為“21世紀(jì)最具發(fā)展?jié)摿Φ木G色工程材料”。鎂合金密排六方的晶體結(jié)構(gòu)使其在室溫下塑性和韌性較差,成為制約其加工應(yīng)用的關(guān)鍵問(wèn)題。本文以AZ63鎂合金為試驗(yàn)材料,采用累積疊軋工藝(Accumulative Roll Bonding,ARB)制備了鎂合金板材,利用組織觀察、力學(xué)性能測(cè)試等研究了累積疊軋工藝對(duì)鎂合金板材界面焊合行為、組織及性能影響,獲得了鎂合金累積疊軋界面焊合機(jī)制與塑性變形機(jī)理以及晶粒細(xì)化機(jī)制,對(duì)豐富鎂合金劇塑性變形理論、高性能鎂合金板材生產(chǎn)與應(yīng)用具有一定的理論依據(jù)和指導(dǎo)意義。在累積疊軋?jiān)囼?yàn)中,溫度分別為250℃、300℃、350℃、400℃,每個(gè)溫度下進(jìn)行5個(gè)道次ARB變形。結(jié)果表明,累積疊軋工藝能夠顯著細(xì)化鎂合金板材的顯微組織、提高鎂合金的強(qiáng)度和塑性,且隨著道次的增加組織均勻性改善明顯。其中,經(jīng)ARB1變形后鎂合金伸長(zhǎng)率提升了44%、經(jīng)ARB3變形后強(qiáng)度由232MPa提高到282MPa。變形溫度和首道次變形量是制約界面結(jié)合質(zhì)量的關(guān)鍵因素,適當(dāng)提高加熱溫度、延長(zhǎng)保溫時(shí)間,可有效改善鎂合金塑性變形能力、有利于界面焊合;多道次疊軋變形可有效改善界面焊合質(zhì)量,累積疊軋的界面焊合機(jī)制為再結(jié)晶結(jié)合機(jī)制。在鎂合金累積疊軋變形初期,孿生發(fā)揮著重要作用,由于孿晶的產(chǎn)生能夠促進(jìn)基面滑移的開(kāi)動(dòng),同時(shí)激發(fā)了大量再結(jié)晶,進(jìn)而導(dǎo)致剪切帶的產(chǎn)生。隨著變形程度的增加,剪切帶可通過(guò)擴(kuò)展和寬化容納更多外部變形,提高材料塑性變形能力。在變形持續(xù)累積到ARB3后,再結(jié)晶程度增加,取代剪切帶組織。結(jié)合鎂合金塑性變形機(jī)理和再結(jié)晶形核機(jī)制,建立了孿晶誘導(dǎo)再結(jié)晶形核模型。在孿晶交錯(cuò)處更容易造成應(yīng)力集中,為再結(jié)晶提供形變儲(chǔ)能,使孿晶界成為有效形核點(diǎn)。孿晶相互交叉作用越強(qiáng)烈,有利的形核位置就越多,進(jìn)一步促進(jìn)再結(jié)晶,組織的細(xì)化效果更顯著。對(duì)于AZ63鎂合金的累積疊軋工藝,其晶粒細(xì)化過(guò)程主要受孿晶誘導(dǎo)再結(jié)晶和動(dòng)態(tài)再結(jié)晶共同控制。
[Abstract]:Magnesium alloys have a broad application prospect and potential in the fields of electronic communication, automobile manufacturing and aerospace, and are known as "the most potential green engineering materials in the 21st century". The crystal structure of dense hexagonal magnesium alloy makes its ductility and toughness poor at room temperature, which is a key problem restricting its processing and application. In this paper, AZ63 magnesium alloy was used as the experimental material and the cumulative stacked rolling process (Accumulative Roll Bonding,ARB) was used to prepare the magnesium alloy sheet. The bonding behavior of the cumulative stacked rolling process on the interface of magnesium alloy sheet was studied by means of microstructure observation and mechanical property test. The effect of microstructure and properties on the bonding mechanism, plastic deformation mechanism and grain refinement mechanism of accumulative stacking interface of magnesium alloy were obtained, which enriched the theory of superplastic deformation of magnesium alloy. The production and application of high-performance magnesium alloy sheet has certain theoretical basis and guiding significance. In the cumulative rolling test, the temperatures are 250 鈩，

本文編號(hào)：2418353