Powder Metallurgy Processing of an Al-0.7Mg-0.4Si-(Sn) Alloy

Abstract

6xxx series (Al-Mg-Si) alloys represent one of the most widely used systems for automotive applications, offering an advantageous balance of thermal conductivity, formability, and strength. In a wrought context, over 45 unique 6xxx alloy chemistries are available to end-users yet in the powder metallurgy (PM) sector there is but one (PM6061). Research in this project thus seeks to devise PM systems that are lean in Mg/Si contents so as to invoke maximum thermal conductivity. Chemistries comparable to wrought alloy 6063 (Al-0.7Mg-0.5Si) were investigated for this purpose. The response of this material to press-and-sinter processing was studied with an emphasis on ascertaining the effects of small additions of tin, and variations in key PM processing parameters. Metallurgical characterization of the sintered product included microstructural analyses, density measurements, thermal diffusivity testing, and mechanical testing. Select formulations achieved >99% theoretical density and thermal conductivities that closely matched those of the wrought equivalent.