晶粒细化对铸造Al-7Zn-2.5Mg-Cu合金性能的影响  

Influence of Grain Refinement on Properties of Cast Al-7Zn-2.5Mg-Cu Alloys

作　　者：陈晓[1] 黄胜[1] 

机构地区：[1]福州大学机械工程及自动化学院

出　　处：《特种铸造及有色合金》2012年第11期991-995,共5页Special Casting & Nonferrous Alloys

基　　金：福建省自然科学基金资助项目(2009J01245)

摘　　要：在铸造Al-7Zn-2.5Mg-Cu合金中分别加入0.2%、0.5%、0.8%和1.2%的Al-5Ti-B细化剂,研究了细化剂加入量对合金的微观组织、抗拉强度和热裂倾向的影响。结果表明,Al-5Ti-B细化剂明显细化Al-7Zn-2.5Mg-Cu合金的组织。随着细化剂添加量的增加,晶粒尺寸先减小,后稍微增大,在加入量为0.8%时,晶粒尺寸最小,为66μm。随着晶粒尺寸的减小,Al-7Zn-2.5Mg-Cu合金的共晶体数量增多,抗拉强度增加,热裂倾向减小。抗拉强度与晶粒尺寸的关系为σb=47.22711+1325.35477×d-1/2,热裂倾向与晶粒尺寸的关系为H=41.73912+0.5733×d。共晶组织也影响合金的抗拉强度和热裂倾向。试验范围内,共晶组织增多,抗拉强度降低,热裂倾向先降低后升高。Microstructure, tensile strength and hot cracking tendencies of cast Al-7Zn-2.5Mg-Cu alloy with Al-5Ti-B grain refiner contents including 0, 0.2%, 0.5%, 0.8% and 1.2% were investigated. The results show that grains of Al-7Zn-2.5Mg-Cu alloy are refined obviously by adding Al-5Ti-B grain refiner. With increasing in the refiner addition, the grain size is decreased firstly and then slightly increased. The smallest grain size with 66 μm can be observed with 0.8%grain refiner. As grain size decreases, the number of eutectic is increased, resulting in the improvement of tensile strength and decrease of hot cracking tendencies of cast Al-7Zn-2.5Mg-Cu alloy. Tensile strength and grain dimension follow the relationship of σb=47.227 11＋1 325.354 77×d-1/2, and hot cracking tendencies and grain dimension follow the relationship of H=41.739 12＋0.573 3×d. Eutectic phase also affects the tensile strength and hot cracking tendency of the alloy. Under experimental conditions, tensile strength is decreased and hot cracking tendency is decreased firstly and then raised with increasing in the eutectic number.

关 键 词：铸造Al-Zn-Mg-Cu合金 细化 微观组织 热烈倾向 抗拉强度 

分 类 号：TG27[金属学及工艺—铸造]