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利用EBSD,TEM和压缩测试研究了平均晶粒尺寸为0.8—5.2μm的烧结细晶Al的微观组织与力学性能.研究表明,随着晶粒尺寸的减小,烧结细晶Al的力学行为发生转变:平均晶粒尺寸小于1.3μm时,由于可动位错源的缺失,细晶Al的应力应变曲线表现出明显屈服降落现象;平均晶粒尺寸减小至0.8μm时,细晶Al在变形过程中晶粒内部很少形成或不形成位错界面,其应力-应变曲线表现为屈服后缺乏加工硬化.平均晶粒尺寸为5.2μm的细晶Al相比于常规粗晶Al来说,由于晶界作用增加以及氧化物颗粒的影响,其位错界面取向差角的演变速率要更快.总体来说,由于氧化物颗粒的贡献,烧结细晶Al的强度要高于常规形变退火方法制备的具有相同平均晶粒尺寸的细晶Al,对于平均晶粒尺寸小于1.3μm的细晶Al,位错源缺失也起着一定的强化作用.
The microstructure and mechanical properties of sintered fine-grained Al with an average grain size of 0.8-5.2 μm were investigated by EBSD, TEM and compressive tests. The results show that the mechanical behavior of sintered fine-grained Al occurs as the grain size decreases Transformation: When the average grain size is less than 1.3μm, the stress-strain curve of fine-grained Al shows obvious yield-fall due to the absence of movable dislocation sources. When the average grain size decreases to 0.8μm, the deformation of fine-grained Al In the process, there is little or no dislocation interface formed in the grain, and the stress-strain curve shows a lack of work-hardening after yielding. Fine grain Al having an average grain size of 5.2 μm As compared with conventional coarse grain Al, The grain boundary effect and the influence of oxide particles, the rate of evolution of the orientation difference angle at the dislocation interface is faster.In general, the strength of sintered fine-grained Al is higher than that of the conventional deformation annealing method due to the contribution of the oxide particles Of fine-grained Al with the same average grain size, and for the fine-grained Al with an average grain size of less than 1.3 [mu] m, the dislocation source also plays a role of strengthening.