采用雾化粉体＋挤压（Ato ＋Ext）、雾化粉体＋热等静压＋挤压（Ato ＋HIP ＋Ext）、低温球磨＋挤压（Cryo ＋Ext）、低温球磨＋热等静压＋挤压（Cryo ＋HIP ＋Ext）四组不同的工艺制备块体纳米晶／细晶铝，并测定了室温拉伸性能，分析了这些块体材料的拉伸应力-应变曲线，利用透射电镜和扫描电镜观察了试样断口附近的位错活动及试样的断口形貌，讨论了其变形机理和断裂机理。研究结果表明：球磨粉体制备的块体纳米晶铝的强度远高于雾化粉体制备的块体超细晶铝，四组块体材料在拉伸过程中均不存在加工硬化现象；块体超细晶铝在拉伸过程中发生了明显的位错运动，对于块体纳米晶铝，尺寸≤100nm 的晶粒在拉伸过程中内部基本不发生位错运动；块体超细晶铝大部分区域发生穿晶断裂，而块体纳米晶铝基本发生沿晶断裂。
In this study,four groups of different process es of Ato +Ext,Ato +HIP +Ext ,Cryo +Ext and Cryo +HIP +Ext were set to prepare bulk nanocrystalline /ultrafine-grained Al,and the mechanical properties of the bulks were determined.Then,tensile stress was analysized,the fracture morphology and corresponding dislocation morphology were observed respectively by scanning electron mi-croscopy (SEM).Finally,the deformation and fracture mechanism were discussed.The result showed that the sample made with as-milled powder had an excellent strength compared to sample made with atomized powder.The indication of work hardening had not been observed in all tensile stress strain curves of the four samples.The dislocation movement,which could been seen obviously in ultrafine-grained samples,appeared only in large grain(≥ 100nm)in nanocrystalline samples.The tensile specimen of the bulk prepared via Ato +HIP +Ext exhibited a transcrystalline fracture,while intergranular fracture was happened to the other specimens.
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