细化剂对7050铝合金铸态显微组织的影响

Effect of grain refiner on microstructure of 7050 aluminum alloy with casting temper

观察了英国LSM公司生产的Al-3Ti-0.2C细化剂和国产Al-5Ti-1B细化剂的内部粒子形貌,系统研究了上述两种细化剂对7050铝合金铸态显微组织的影响。研究表明,当添加质量分数为0.3%～0.9%的Al-3Ti-0.2C细化剂时,7050铝合金平均晶粒度在106μm～210μm范围内,其最佳添加量为0.3%～0.45%。添加质量分数为0.45%的Al-3Ti-0.2C细化剂后,7050铝合金铸锭由蔷薇形枝晶组成,平均晶粒度为120μm,添加同样量的Al-5Ti-1B细化剂后,7050铝合金铸锭组织由近球形等轴晶构成,平均晶粒度为105μm。在10 min～120 min保温范围内,随着时间延长,Al-3Ti-0.2C细化剂比Al-5Ti-1B细化剂的细化失效现象更明显。

The particle morphology of refiners both produced by LSM as Al-3Ti-0.2C and that produced by domestic works as Al-5Ti-IB has been investigated. The effect of the above mentioned refiners on microstructure of 7050 aluminum alloy with casting temper has been studied systematically. The study results show that the average particle size of 7050 aluminum alloy will be l06 μm - 20l μm while the adding amount of Al-3Ti-O. 2C refiner is 0 - 0.9% ;the optimum amount is 0.3% -0.45% ;or 0.45% addition of AI-3Ti-O. 2C refiner the microstructure of 7050 aluminum alloy slab is composed mainly by rosette crystals with average crystal size of l20μm ;while to add the same amount of Al-5Ti-lB refiner, the micro-structure will be composed by sub-spherical isometric crystals with average crystal size of l05 μm. During time holding in the scope of l0 min - l20 min, the refining effect being faded gradually with time going; the refining fading of Al-3Ti-0.2C refiner is more evident than that of Al-5Ti-lB refiner.