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采用金相显微镜(OM)、扫描电镜(SEM)和透射电镜(TEM)等手段,研究了Pr对Al-5Cu合金在不同状态下的显微组织和力学性能的影响,并分析了Pr的存在形式与作用机理。结果表明,Pr可以有效细化Al-5Cu合金中的α-Al枝晶,且枝晶尺寸会随着Pr含量的增加而呈现先减小而后增加的趋势,在Pr含量为0.3%时最小;Pr变质Al-5Cu合金适宜的热处理工艺为540℃×8 h+165℃×10 h;经0.3%的Pr变质合金在165、185和250℃时效峰值硬度下θ’相的平均长度相对未变质Al-5Cu合金分别减小23.2%、25.6%和31.1%,且其析出量也要明显多于后者;随着Pr含量的增加,合金的抗拉强度和伸长率都表现为先增加而后降低的趋势,在Pr含量为0.3%时最大;0.3%的Pr变质Al-5Cu合金的常温和高温抗拉强度和伸长率都要高于未变质的Al-5Cu合金,其主要作用机制为细晶强化和第二相强化。
The effects of Pr on the microstructure and mechanical properties of Al-5Cu alloy under different conditions were investigated by means of OM, SEM and TEM. The existence of Pr Form and mechanism of action. The results show that Pr can effectively refine the α-Al dendrites in Al-5Cu alloy, and the dendrite size decreases first and then increases with the increase of Pr content, which is the smallest when the Pr content is 0.3% The suitable heat treatment process of Pr-modified Al-5Cu alloy is 540 ℃ × 8 h + 165 ℃ × 10 h. The average length of θ ’phase at 0.3% Pr metamorphic alloy is relatively non-degenerated at aging peak hardness of 165, 185 and 250 ℃ Al-5Cu alloy decreased by 23.2%, 25.6% and 31.1%, respectively, and the amount of precipitation was significantly higher than that of the latter. With the increase of Pr content, the tensile strength and elongation of Al-5Cu alloy firstly increased and then decreased The maximum tensile strength and elongation of 0.3% Pr-modified Al-5Cu alloy are higher than those of unaltered Al-5Cu alloy. The main mechanism of action is fine grain Strengthen and strengthen the second phase.