Effect of Quench Rate on PFZ Width in 7xxx Aluminum Alloys

The effect of quench rate on the width of precipitate free zone was examined in aluminum alloys 7075 and 7050. It was determined that at quench rates greater than 60°C/sec., vacancy depletion dominated. At slower quench rates, it was determined that solute depletion dominated the precipitate free zone. The critical vacancy concentration for precipitation was established as a function of quench rate.