Alloy Design for Additive Manufacturing of Shape Memory Alloys

Additive Manufacturing (AM) has revolutionized metal component production, highlighting the need for suitable metal alloys. This presentation focuses on the alloy design procedure for additive manufacturing, with a specific emphasis on challenges in high temperature shape memory alloys (HTSMA), ternary alloys, and solidification defects.

The alloy design procedure entails defining objectives, conducting a literature review, selecting alloy compositions, performing small-scale testing, iterative optimization, and characterization/validation. The talk highlights the challenges that arise in alloy design for AM, particularly in SMA. SMA alloys present challenges due to complex phase transformations and the need for precise control over transition temperatures and functional properties. Additionally, ternary alloys lack comprehensive data in existing software, making their design and optimization more challenging. Furthermore, the solidification range plays a crucial role in AM, as it can lead to cracking during melt pool solidification, presenting a significant challenge in alloy design.

Rapid alloy and powder-making tools such as lab scale ultrasonic powder atomizers offer a solution by expediting small-scale testing. It enables rapid evaluation of phase transformation behavior of atomized powder and follow-up single track experiments helps in identification of solidification defects in AM of SMA alloys. As such multiple NiTi-X alloys are evaluated based on their printability using computational tools. Printability is further investigated through single track experiments. Finally, each alloy is atomized to make enough of powder and further characterized. Therefore, this presentation showcases the role of rapid alloy-making instruments in addressing cracking challenges specifically for NiTi-X as a desirable high-temperature shape memory alloy.