纳米氧化铝弥散强化铜的放电等离子体烧结动力学及机制

Sintering kinetics and mechanism of nano Al_2O_3 particles dispersion strengthened copper by spark plasma sintering

利用经典热压模型,系统研究纳米氧化铝颗粒弥散强化铜的放电等离子烧结(SPS)致密化过程与机理。结果表明,放电等离子烧结初期,氧化铝弥散强化铜的致密化过程由晶界滑移和晶界扩散共同控制。随保温时间延长,烧结机制转变为由晶界滑移所主导。烧结后期致密化主要以塑性变形的方式进行。纳米氧化铝颗粒抑制了铜的烧结致密化,导致材料的密度降低。抑制机理为氧化铝颗粒阻碍晶界和位错运动,导致晶界滑移和塑性变形的激活能提高,从而增大致密化抗力。在外力和纳米氧化铝颗粒的共同作用下,塑性变形的主要形式为孪生。

The effects of nano Al2O3 particles on Al2O3 dispersion strengthened copper prepared by spark plasma sintering(SPS)were studied systematically by using the hot-pressing sintering model.The results show that the densification process is dominated by grain boundary diffusion and sliding in the early stage of sintering,followed by the grain boundary sliding.And the plastic deformation occurs in the last stage of sintering.The density of the copper strengthened by Al2O3 particles decreases.The Al2O3 particles existing along the grain boundaries can inhibit the densification of copper because the particles can block the movement of grain boundaries and dislocation,which indicates that the densification process required higher activation energy.The deformation mode is mainly twinning,which is resulted from co-existence of the shear stress and the pinning of Al2O3 particles.