Chementator: Stronger die cast parts  

High-pressure die-cast (HPDC) aluminum alloys cannot normally be heated to high temperatures due to the presence of pores containing entrapped gases, which lead to the formation of surface blisters. CSIRO Materials Science and Engineering (Melbourne, Australia; edlinks.chemengonline.com/7371-548) has found that blistering can be avoided by using shorter solution-treatment times at lower temperatures. CSIRO says its process also offers major improvements in tensile-mechanical and other properties. "We envisage that this will make it possible to use HPDC components more widely in load-carrying structural and safety applications," says Roger Lumley a researcher at CSIRO Materials Science and Engineering. Also, treated parts exhibit thermal conductivity about 20% above their as-cast status, opening up potential applications in engines or transmissions. Surprisingly, Lumley says, fatigue resistance of aluminum HPDC components, heat-treated with the new process, can be as high as for some wrought aluminum products, tending toward limiting behavior usually observed in steel. When Al Alloy 360 is treated using a conventional, prolonged solution treatment of 16 h at 545°C, severe surface blistering and discoloration occurs, and…