搅拌摩擦加工铸态铝铁合金的显微组织

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

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。

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