Effect of powder metallurgy synthesis parameters for pure aluminium on resultant mechanical properties

In this work, pure aluminium powders of different average particle size were compacted, sintered into discs and tested for mechanical strength at different strain rates. The effects of average particle size (15, 19, and 35m), sintering rate (5 and 20 degrees C/min) and sample indentation test speed (0.5, 0.7, and 1.0mm/min) were examined. A compaction pressure of 332MPa with a holding time of six minutes was used to produce the green compacted discs. The consolidated green specimens were sintered with a holding time of 4h, a temperature of 600 degrees C in an argon atmosphere. The resulting sintered samples contained higher than 85% density. The mechanical properties and microstructure were characterized using indentation strength measurement tests and SEM analysis respectively. After sintering, the aluminium grain structure was observed to be of uniform size within the fractured samples. The indentation test measurements showed that for the same sintering rate, the 35m powder particle size provided the highest radial and tangential strength while the 15m powder provided the lowest strengths. Another important finding from this work was the increase in sintered sample strength which was achieved using the lower sinter heating rate, 5 degrees C/min. This resulted in a tangential stress value of 365MPa which was significantly higher than achieved, 244MPa, using the faster sintering heating rate, 20 degrees C/min.