铝合金粉末锻造及致密化成形技术研究
发布时间：2018-08-25 11:44
【摘要】：目前,铝合金的性能已经不能完全满足航空航天、国防军工乃至民用产品的要求,尤其是“以铝代钢”的发展要求,亟需开发高性能铝合金产品。粉末冶金铝合金具有“减重”与“近净成形”双重优势,但存在一个重要问题：烧结体中有孔隙,会严重影响产品性能。粉末锻造能够消除粉末冶金材料中的孔隙,获得全致密、高性能、复杂形状零部件。本文以制备高性能复杂形状粉末冶金铝合金产品为目的,运用扫描电境、透射电境、X射线衍射、物理热模拟、性能测试等综合实验手段,开展了铝合金粉末锻造及致密化成形技术研究,为粉末冶金铝合金的推广应用提供了理论依据和技术支撑。采用高温热压缩实验,系统研究了粉末冶金2A50铝合金在温度为300～500℃、应变速率为0.001～1s-1范围内的高温流变行为,发现流变应力曲线最终阶段未达到稳态流变而应力持续缓慢增加,动态再结晶过程受到抑制,晶粒不长大。研究表明,这主要是由于基体中存在纳米Al2O3(20～50 nm),高温稳定性优异,能够在高温下继续阻碍位错运动和品界迁移,提高了高温变形抗力,抑制了晶粒长大。利用热模拟实验数据,建立了粉末冶金2A50铝合金高温流变本构方程,成功试制出表面质量良好的粉末冶金铝合金锻造轮毂,在细晶强化和弥散强化双重作用下,粉末冶金铝合金轮毂具有比相似成分变形铝合金更优异的力学性能和抗应力腐蚀性能。采用旋转锻造技术成功将Φ20mm粉末冶金纯铝和2024铝合金烧结坯制备成Φ1mm丝材,屈强比接近于1。与工业纯铝1050相比,由于纳米A1203的弥散强化作用,粉末冶金纯铝具有更为优异的室温和高温力学性能,500℃退火后,6μm铝粉制备的纯铝丝材屈服强度和抗拉强度均接近工业纯铝1050的2倍,延伸率达到7.2%。粉末冶金2024铝合金丝材T6热处理态的力学性能十分优异,屈服强度达547 MPa,抗拉强度达598 MPa,延伸率为9.1%。提出粉末液相锻造技术,成功制备出全致密、高性能的粉末冶金2A50铝合金和h-BN/Al复合材料。当液相体积分数达100%时,由于纳米A1203阻碍晶界迁移,粉末冶金2A50铝合金品粒不发生长大。h-BN/Al复合材料相对密度达99%以上,界面结合良好；2 gm铝粉制备的h-BN/Al复合材料硬度、抗压强度、断裂应变等综合力学性能最优。
[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，
本文编号：2202782
[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，
本文编号：2202782
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