Processamento de pós de alumínio por forjamento multidirecional

Abstract

One of the possible routes for aluminum recycling is processing through powder metallurgy (PM), which enables the reduction of pollutant emissions and an increase in process efficiency. In this work, a variation of aluminum processing via PM is proposed, employing a severe plastic deformation (SPD) technique – multidirectional forging (MDF). After characterization, the powders were compacted using 5, 15, and 30 MDF cycles with a strain amplitude of ~0.90 per cycle and an axial stress of 412 MPa. Part of the material was subjected to various heat cycles to determine the optimal conditions. The temperatures and sintering times that yielded the best results were 550°C for 90 minutes and 600°C for 120 minutes. Both sintered and non-sintered specimens were characterized in terms of hardness and mechanical behavior to evaluate the influence of mechanical and thermal processing of aluminum powders on their properties. The hardness test results indicated that the number of MDF cycles during powder compaction did not affect either the green compact hardness or the hardness after sintering. Additionally, there was a trend of decreasing material hardness with increasing sintering temperature and time. In compression tests, a trend of increasing yield strength and compressive strength was observed with an increasing number of compaction cycles for non-sintered samples. For sintered samples, however, the influence of the number of MDF cycles on the mechanical strength of the material was eliminated. The number of compaction cycles did not affect the ductility of the processed aluminum powders. Sintering generally increased the mechanical strength and ductility of the specimens.