均勻化升溫速率對7N01 鋁合金組織與力學性能的影響Effect of homogenization heating rate on microstructure and mechanical properties of 7N01 aluminum alloy

采用光學顯微鏡、掃描電鏡、電子探針顯微鏡、透射電鏡和常溫拉伸等測試方法研究均勻化升溫速率對7N01 鋁合金顯微組織和力學性能的影響。結(jié)果表明：與升溫速率較快的均勻化制度相比，采用升溫速率小于100℃/h 的慢速升溫均勻化制度更有利于細小彌散Al3Zr 粒子的析出，使Al3Zr 粒子分布均勻；細小彌散的Al3Zr 粒子能有效地阻止再結(jié)晶晶界的遷移，抑制再結(jié)晶的發(fā)生。隨著均勻化升溫速率由500 ℃/h 降低到20 ℃/h，析出的Al3Zr 粒子數(shù)量增加，尺寸減小，析出相體積分數(shù)和半徑的比值φ/r 由75.8 μm^-1 增大到359.1 μm^-1，使得Al3Zr粒子對晶界的釘扎力增大，因此合金的再結(jié)晶分數(shù)相應(yīng)地由31.92%逐漸降低到1.32%；保留下來的大量位錯和未再結(jié)晶組織提高了合金的綜合力學性能。

The effects of homogenization heating rate on the microstructure and mechanical properties of 7N01 aluminum alloy were investigated by optical microscopy (OM),scanning electron microcopy (SEM),electron probe microanalyzer (EPMA),transmission electron microcopy (TEM) and tensile test. The results show that using a slow homogenization heating rate less than 100 ℃/h is favorable for the precipitation of fine and uniformly distributed Al3Zr particles compared with fast homogenization heating rate. The dispersion distribution of fine Al3Zr particles can decrease the recrystallized fraction since the Al3Zr particles can effectively prevent the migration of recrystallization grain boundary. When the homogenization heating rate decreases from 500 ℃/h to 20 ℃/h,the average dispersoid number increases,the particle size decreases,and the ratio of volume fraction (φ) to radius (r) of the precipitate (φ/r) increases from 75.8 μm^-1 to 359.1 μm^-1,which improves the dragging effect of Al3Zr particles on the grain boundaries and leads to a reduction in the recrystallized fraction from 31.92% to 1.32%. Meanwhile,the unrecrystallized microstructures containing profuse dislocations enhance the comprehensive mechanical properties of the studied alloy.

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