Effect of degassing parameters on sinterability of Al/B₄C powder mixture

Abstract

The 6061-Al powder was degassed under vacuum, argon and hydrogen before mixing with 5 mass-%B₄C particles. After compaction, the supersolidus liquid phase sintering was performed at 630°C under high purity argon and nitrogen atmosphere. The purpose of this experimental plan was to study the effect of different degassing and sintering environments on the compressibility and sinterability of Al/B₄C composites. The efficacy of degassing condition in-terms of sintered density is in the order of hydrogen, argon and vacuum (highest). Al/B₄C composite sintered under argon atmosphere after vacuum degassing showed ∼8% higher sintered density as compared to the sample with similar condition except degassing. Al/B₄C composite sintered under N₂ atmosphere without degassing showed ∼89% density and 65 HRB while the composite sintered under N₂ atmosphere after degassing in vacuum showed ∼98% density and 89 HRB with faded boundaries between 6061-Al particles in the microstructure.

Keywords:

• Al/B₄C composite
• Degassing
• Sintering
• Microstructure
• Hardness

Acknowledgements

Z. Asghar would like to thank Muhammad Musaddiq for help in degassing and sintering experiments. The authors acknowledge the cooperation of members of Powder Processing Group.