原位Al_2O_3颗粒对近液相线铸造Al-Cu合金二次加热组织的影响

Effect of In-situ Al_2O_3 Particles on Reheating Microstructure of Near-liquidus Casting Al-Cu Alloy

采用原位反应近液相线铸造方法制备Al2O3p/Al-Cu基复合材料,对其进行二次加热,研究晶粒的形貌演变和长大规律。用光学显微镜观察组织、I mage Tool软件测量平均晶粒尺寸、I mage pro plus软件测量合金液相率,并与理论计算数值比较。结果表明,在590℃保温10、20、40、60 min后,Al2O3p/Al-Cu基复合材料的平均晶粒尺寸比不含Al2O3颗粒的基体合金减少15～25μm,液相率依次为11.6%、13.2%、15.3%、20.9%,较基体合金的液相率小且增长速度慢。说明Al2O3在合金的二次加热过程中对晶粒长大行为具有明显的抑制作用,从而为优化半固态组织提供了一种新思路。

The semi-solid Al2O3/Al-Cu alloys cast with in-situ near-liquidus casting technology were reheated, and its microstructural evolution and grain growth mechanism were studied by means of optical microscope, the grain sizes and liquid were measured using Image tool, Image pro plus, compared with theoretical calculation. The results indicated that the in-situ Al2O3 particles can not only keep liquidus cast Al-Ou alloy with fine and globular microstructure, but alsocontrol evidently grains growth by pinning effect during reheating. The results indicate that under the combination of reheating temperature 590 ℃ and holding time 10.20.40.60 min, The average grain size of Al2O3/ Al-6.8Cu alloy decreased by 15- 25μm, liquid volume fraction were 11.6%, 13.2%, 15.3%, 20.9% and the growth speed was slower than that of Al-6.8Cu alloy. That in-situ Al2O3 particle can control the grain sizes, then, the conclusion will offer one kind of new mentality for optimizing semi- solid microstructure.