纯铝粉末多孔烧结材料等通道转角挤压致密化行为研究

Study on densification behavior of sintered powder pure aluminum during equal channel angular extrusion process

对纯铝粉末烧结材料进行等通道转角挤压实验,结果表明:经一次挤压后主要变形区组织剪切变形特征明显,内部的孔隙基本闭合,组织明显细化;多道次挤压后,不同挤压路径得到材料组织形态及孔隙闭合效果不同。研究认为,单道次ECAE过程中的孔隙闭合效果取决于试样所处的应力状态,即剪应力和球应力张量的良好匹配是材料获得良好的致密效果的关键。多道次挤压由于变形量的累积和不同的剪切特征不断改变基体及孔隙的形状,使材料进一步致密。

ECAE experiment was carried out for the sintered powder pure aluminum.Experimental results show that the ECAE process has powerful densification effect and the microstructure has obvious shear deformation character after the single pass extrusion;during the multiple processes,the densification effects and the microstructure of material vary with different routines.Analysis shows that in the single ECAE process the closing effect of pore depends on shear deformation character and stress state of material,which is the key factors to obtain high density under large shear plastic deformation and high hydrostatic stress state.According to the strain value accumulation and different shear deformation characters,multiple passes can rearrange the powder particle,change pores shape and make the powder material get higher density.