铜模内径对亚快速凝固K424合金析出相的影响  

Effect of copper-mould diameter on precipitation phase of sub-rapid solidified K424 alloy

作　　者：朱堂葵[1] 杨伟[2] 吴宗锴 刘灵 ZHU Tang-kui;YANG Wei;WU Zong-kai;LIU Ling(School of Electromechanical and Information Technology,Yiwu Industrial and Commercial College,Yiwu 322000,China;School of Aeronautical Manufacturing Engineering,Nanchang Hangkong University,Nanchang 330063,China)

机构地区：[1]义乌工商职业技术学院机电信息学院,浙江义乌322000 [2]南昌航空大学航空制造工程学院,江西南昌330063

出　　处：《材料热处理学报》2021年第3期80-88,共9页Transactions of Materials and Heat Treatment

基　　金：义乌工商职业技术学院重点科研项目(ZD2020CS414-02);国家自然科学基金(52061032,51461032);江西省教育厅资助项目(GJJ180513)。

摘　　要：采用阶梯铜模喷铸制备了不同内径的亚快速凝固K424合金,采用时效处理研究了原始非平衡组织状态对快冷合金γ′析出相析出的影响。结果表明:铜模内径的降低可以减弱合金凝固过程中的溶质偏析程度,缩短相变时间,抑制共晶相及析出相形成,有利于获得高固溶组织。经700℃时效30 min处理后,Ф2合金由于形核驱动力高,临界形核半径小,相比Ф6合金优先析出γ′相。当时效温度提高到800℃,低内径铜模基体中可形成均匀分布的析出相,同时形核密度得到显著提高。随时效时间延长,γ′相先快速长大随后缓慢生长,其中Ф2合金由于γ′相过早析出导致其尺寸比相应的Ф6合金更大。析出相析出可以有效增加合金的显微硬度,经800℃时效180 min后Ф2合金硬度高达494 HV0.2,相比原始快冷合金提高13.8%。A sub-rapid solidification K424 alloy with different diameters was prepared by step copper mould casting,and effect of primary non-equilibrium microstructure onγ′precipitation phase of the rapid cooled alloy was studied by aging treatment.The results show that the decrease of the copper mould diameter can reduce the degree of solute segregation during solidification,shorten phase transition time,inhibition of eutectic and precipitated phases formation,which is beneficial to obtain high-supersaturated microstructure.After aging at 700℃for 30 min,theγ′phase is preferentially formed in the alloy with diameter of 2 mm rather than that of the alloy with diameter of 6 mm due to the higher nucleation driving force and smaller critical nucleation radius.When the aging temperature is 800℃,the uniformly distributedγ′precipitation phase can be formed in the copper matrix with low diameter,and the nucleation density is significantly improved.With the increase of aging time,theγ′phase grows fast firstly and then slowly,and theγ′phase size of the alloy with diameter of 2 mm is larger than that of the alloy with diameter of 6 mm due to theγ′phase premature precipitation.The precipitation phase can effectively increase the microhardness of the alloy,the hardness of the alloy with diameter of 2 mm after aging at 800℃for 180 min is 494 HV0.2,which is 13.8%higher than that of the as-received rapid solidified alloy.

关 键 词：K424合金 冷却速率 非平衡凝固 铜模内径 

分 类 号：TG132.3[一般工业技术—材料科学与工程]