搅拌摩擦加工铸态铝铁合金的显微组织

采用普通熔铸法制备含铁3%(质量分数)的铝铁二元合金,研究多道次往复搅拌摩擦加工(Friction stir processing,FSP)对合金显微组织的影响。结果表明:进行1~3道次往复FSP后,各道次加工区组织不均匀;随着加工道次的增加,组织均匀细化程度增大。合金铸态组织由α-Al和粗大针状Al3Fe相组成,经3道次FSP后,搅拌区组织明显细化。原始铸态组织转变为细小等轴的再结晶晶粒,尺寸为2~5μm,并且部分晶粒中出现层错;粗大的Al3Fe针状相被破碎成长度小于1μm的细小粒状,弥散分布在铝基体晶界和晶粒内部,细化的Al3Fe粒子呈现孪晶结构。

Microstructure of friction stir processed as-cast Al-Fe alloy

Al-3%Fe(mass fraction) binary alloy was prepared by fusion casting.The effect of reciprocating multi-pass friction stir processing(FSP) on the microstructure of the alloy was studied.The results show that the microstructure of each pass in stir zone is non-uniform after one to three passes reciprocating FSP.With the increase of processing passes,the degree of uniformity and refinement of the microstructure increases.The as-cast alloy is composed of the α-Al and coarse needle Al3Fe phases.The microstructure in stir zone is significantly refined after three passes FSP.The as-cast microstructure in the stir zone is changed into fine equiaxed recrystallized grains with the size of 2-5 μm,and stacking fault appears in some grains.Coarse needle Al3Fe phases are broken into granular phases with the length of less than 1 μm,and disperse in Al matrix grain boundary and grain interior.Refined Al3Fe particles present twin structure.