Accelerated Development of Al Alloys for Additive Manufacturing

Al alloys can exhibit very high-strengths due to nano-scale precipitates that typically form during post synthesis heat treatments. A key limitation of many of these alloys, however, is their lack of thermal stability at moderate temperature (e.g., T > 200 °C) as well as limited processing flexibility. Specifically, the number of Al alloys systems that can be synthesized via Additive Manufacturing (AM) techniques is relatively small due to issues with hot-cracking. Here we discuss the development of Al-Ce-based alloys for AM processing that show both excellent processing flexibility and nano-scaled microstructures that exhibit enhanced thermal stability relative to precipitation-strengthened Al alloys. We have used a combinatorial approach to print bulk samples over large composition ranges using multiple feedstock powders. The compositional dependence of the mechanical behavior can be rapidly characterized using hardness testing to correlate with the phase stability and microstructural evolution. The rate-controlling deformation mechanisms for the different compositions and structures can then be identified. This approach helps to accelerate the design and development of alloys for additive manufacturing.