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与传统粗晶金属材料相比,纳晶金属具有特殊的变形机理。为了探索纳晶金属的变形机理,以等离子蒸发结合热压烧结制备的块体纳晶镍为研究对象,进行了准静态压缩力学性能测试,并且利用XRD和TEM技术对试样压缩前和压缩后的微结构演化进行了研究。结果表明:块体纳晶镍表现出较高的压缩强度和较好的韧性,且强度和韧性均具有率相关性。同时,纳晶镍压缩变形后晶粒尺寸较压缩前减小,但其微应变增加。结合纳晶镍的力学行为和压缩过程中微结构的演化,预测晶界位错运动和晶界滑移的联合机制是块体纳晶镍压缩过程中塑性变形的主要机理。
Compared with the traditional coarse crystalline metal materials, nanocrystalline metal has a special deformation mechanism. In order to explore the deformation mechanism of nanocrystalline metal, the bulk nanocrystalline nickel prepared by plasma evaporation combined with hot-pressing sintering was investigated. The quasi-static compressive mechanical properties of the nanocrystalline nickel were investigated. The microstructures of nanocrystalline metal before compression and after compression The microstructure evolution has been studied. The results show that the bulk nanocrystalline Ni shows higher compressive strength and better ductility, and the strength and toughness have a rate dependence. At the same time, the grain size of nanocrystalline Ni decreases after compressive deformation, but its micro-strain increases. Combined with the mechanical behavior of nanocrystalline nickel and the microstructure evolution during compression, the combined mechanism of predicting grain boundary dislocation motion and grain boundary slip is the main mechanism of plastic deformation in nanocrystalline nickel during compression.