The Effect of Simple Shear Extrusion on the Texture and Porosity Content of Al/Al۲O۳ Composites

In this study, aluminum/alumina composites with ۱ and ۳ vol% reinforcement particles were produced using powder metallurgy (PM); this was then followed by simple shear extrusion (SSE). Three SSE inserts with different distortion angles (α) were used in the SSE equipment. Three pressure values of ۴۰۰, ۶۰۰ and ۸۰۰ MPa were selected for powder compression. Additionally, three different temperatures of ۵۳۰, ۵۵۰ and ۵۷۰°C were chosen to evaluate the suitable sintering temperature and achieve the optimal SSE process. The effect of post-sintering annealing treatment on SSE feasibility was also investigated. In addition, porosity was measured by the Archimedes method and the microstructure of samples was evaluated using optical and scanning electron microscopy. Evaluation of the crystalline texture was examined by the X-ray method. It was found that the pressure of ۸۰۰ MPa was the optimal value for the cold compression of powders and the temperature of ۵۷۰℃ was the best sintering temperature. It was also observed that the temperatures ۴۰۰℃ and ۴۵۰℃ had no effect on increasing the number of SSE passes. Porosity of the Al-۳ vol% alumina sample was changed from ۵.۷۵% to ۵.۰۲% after three SSE passes with α=۱۰°. A preferred crystallographic texture was not seen due to the amount of effective strain and the presence of micro-pores, but a very low intensity cube texture {۰۰۱} <۱۰۰> was seen in some regions.

Keywords:

Powder metallurgy technique , Simple Shear Extrusion , Porosity measurement , Crystallographic texture , Aluminum/alumina composite