EFFECTS OF ZR ADDITIONS ON THE SINTERING RESPONSE OF AN AL-CU-MG PM ALLOY

摘要

The objective of this work was to investigate the addition of Zr into a recently developed Al-Cu-Mg powder metallurgy alloy (Al- 2.3Cu- 1.6Mg- 0.2Sn). Three variations of the alloy were considered. One was a Zr-free baseline blend, whereas the other two contained 0.2% Zr sourced as either an Al-Zr master alloy or as a pre-alloyed addition within the base aluminum powder itself. A study of the green attributes indicated a slight decrease in green strength within the pre-alloyed system. Testing of the sintering response revealed that each system reached near-full theoretical density and that each alloy demonstrated an excellent combination of tensile properties. The pre-alloyed system was particularly advantageous as it exhibited the greatest yield strength and UTS coupled with an exceptionally high elongation to failure of 10%. However, the most striking advantage of utilizing prealloyed Zr was the ability to all but eliminate distortion in the liquid phase sintered product. It was postulated that this behaviour was related to the formation of a fine dispersion of thermally stable Al_3Zr particles within the Al grains that improved elevated temperature strength and compact rigidity during sintering.