稀土元素La对Zn-Cu-Ti-Mg合金组织和性能的影响

Effect of La on microstructure and properties of Zn-Cu-Ti-Mg alloy

采用熔铸法制备了稀土La元素含量不同的Zn-Cu-Ti-Mg合金,研究了稀土元素La对Zn-Cu-Ti-Mg合金微观组织、断口形貌和力学性能的影响。结果表明：在稀土元素La含量小于1%（质量分数）时,随着La的加入,Zn-Cu-Ti-Mg合金的铸态组织中枝晶明显减少,枝晶臂缩短,晶粒细化;稀土元素与杂质形成化合物,能够清除晶界杂质,抑制杂质元素的有害影响。随着稀土元素含量的升高,Zn-Cu-Ti-Mg合金的硬度和塑性不断提高,强度先减小后增大,断裂机制也由解理断裂变为微孔聚集型断裂。

Zn-Cu-Ti-Mg alloy containing different La content was prepared by casting.The effect of rare earth element La on the microstructure,fracture morphology and mechanical properties of the Zn-Cu-Ti-Mg alloy was studied.The experimental results show that when the content of La is less than 1%（ mass fraction）,the dendrites are reduced,the dendrite arms are shortened,the grains are refined;La forms compounds with impurities,removes impurities in grain boundary and inhibits harmful effects of impurities.With increase of the content of La,the hardness and plasticity of the alloy increase,the strength first decreases and then increases,the fracture mode changes from cleavage fracture to microvoid accumulation fracture.