【摘要】：目前,鋁合金的性能已經(jīng)不能完全滿足航空航天、國(guó)防軍工乃至民用產(chǎn)品的要求,尤其是“以鋁代鋼”的發(fā)展要求,亟需開(kāi)發(fā)高性能鋁合金產(chǎn)品。粉末冶金鋁合金具有“減重”與“近凈成形”雙重優(yōu)勢(shì),但存在一個(gè)重要問(wèn)題：燒結(jié)體中有孔隙,會(huì)嚴(yán)重影響產(chǎn)品性能。粉末鍛造能夠消除粉末冶金材料中的孔隙,獲得全致密、高性能、復(fù)雜形狀零部件。本文以制備高性能復(fù)雜形狀粉末冶金鋁合金產(chǎn)品為目的,運(yùn)用掃描電境、透射電境、X射線衍射、物理熱模擬、性能測(cè)試等綜合實(shí)驗(yàn)手段,開(kāi)展了鋁合金粉末鍛造及致密化成形技術(shù)研究,為粉末冶金鋁合金的推廣應(yīng)用提供了理論依據(jù)和技術(shù)支撐。采用高溫?zé)釅嚎s實(shí)驗(yàn),系統(tǒng)研究了粉末冶金2A50鋁合金在溫度為300～500℃、應(yīng)變速率為0.001～1s-1范圍內(nèi)的高溫流變行為,發(fā)現(xiàn)流變應(yīng)力曲線最終階段未達(dá)到穩(wěn)態(tài)流變而應(yīng)力持續(xù)緩慢增加,動(dòng)態(tài)再結(jié)晶過(guò)程受到抑制,晶粒不長(zhǎng)大。研究表明,這主要是由于基體中存在納米Al2O3(20～50 nm),高溫穩(wěn)定性優(yōu)異,能夠在高溫下繼續(xù)阻礙位錯(cuò)運(yùn)動(dòng)和品界遷移,提高了高溫變形抗力,抑制了晶粒長(zhǎng)大。利用熱模擬實(shí)驗(yàn)數(shù)據(jù),建立了粉末冶金2A50鋁合金高溫流變本構(gòu)方程,成功試制出表面質(zhì)量良好的粉末冶金鋁合金鍛造輪轂,在細(xì)晶強(qiáng)化和彌散強(qiáng)化雙重作用下,粉末冶金鋁合金輪轂具有比相似成分變形鋁合金更優(yōu)異的力學(xué)性能和抗應(yīng)力腐蝕性能。采用旋轉(zhuǎn)鍛造技術(shù)成功將Φ20mm粉末冶金純鋁和2024鋁合金燒結(jié)坯制備成Φ1mm絲材,屈強(qiáng)比接近于1。與工業(yè)純鋁1050相比,由于納米A1203的彌散強(qiáng)化作用,粉末冶金純鋁具有更為優(yōu)異的室溫和高溫力學(xué)性能,500℃退火后,6μm鋁粉制備的純鋁絲材屈服強(qiáng)度和抗拉強(qiáng)度均接近工業(yè)純鋁1050的2倍,延伸率達(dá)到7.2%。粉末冶金2024鋁合金絲材T6熱處理態(tài)的力學(xué)性能十分優(yōu)異,屈服強(qiáng)度達(dá)547 MPa,抗拉強(qiáng)度達(dá)598 MPa,延伸率為9.1%。提出粉末液相鍛造技術(shù),成功制備出全致密、高性能的粉末冶金2A50鋁合金和h-BN/Al復(fù)合材料。當(dāng)液相體積分?jǐn)?shù)達(dá)100%時(shí),由于納米A1203阻礙晶界遷移,粉末冶金2A50鋁合金品粒不發(fā)生長(zhǎng)大。h-BN/Al復(fù)合材料相對(duì)密度達(dá)99%以上,界面結(jié)合良好；2 gm鋁粉制備的h-BN/Al復(fù)合材料硬度、抗壓強(qiáng)度、斷裂應(yīng)變等綜合力學(xué)性能最優(yōu)。
[Abstract]:At present, the performance of aluminum alloy can not fully meet the requirements of aerospace, national defense industry and even civilian products, especially the development requirement of "replacing steel with aluminum", so it is urgent to develop high performance aluminum alloy products. Powder metallurgy aluminum alloy has the advantages of "weight loss" and "near-net forming", but there is an important problem: the porosity in the sintered body will seriously affect the performance of the product. Powder forging can eliminate the pores in powder metallurgy materials and obtain fully dense, high performance and complex shape parts. The purpose of this paper is to prepare high performance and complex shape powder metallurgy aluminum alloy products, using comprehensive experimental means such as scanning electric environment, transmitting electric environment X-ray diffraction, physical thermal simulation, performance testing and so on. The research on powder forging and densification of aluminum alloy is carried out, which provides theoretical basis and technical support for the popularization and application of powder metallurgy aluminum alloy. The high temperature rheological behavior of powder metallurgy 2A50 aluminum alloy in the temperature range of 300 鈩，

本文編號(hào)：2202782