Laser Processing of Hf-Lean NiTiHf Alloy to Induce High Temperature Shape Memory Effects

Development of High Temperature Shape Memory Alloys (HTSMA) over the past decades have gained considerable interest from the automotive and aerospace industry. Among the various alloys systems, NiTiHf has exhibited the highest potential, displaying a significant level of recoverable strain, and exceptional actuation stability throughout thermal and mechanical cycling. However, the high cost of NiTiHf alloys continues to prohibit their adoption beyond the laboratory environment. Cost drivers include alloying a large amount of expensive Hf and needing extensive post-melt processes such as high-temperature-high-vacuum homogenization. The current work demonstrates the application of the Multiple Memory Material Technology to maximize Hf efficacy through rapid homogenization and precise local composition modifications. Results show that processed NiTiHf transformation temperatures increased to match alloys having over 30 wt.% more Hf content, enabling the selective programing of high temperature shape memory capabilities at appropriate actuation-specific regions from an as-cast low-Hf content HTSMA. This allows cost-effective fabrication of HTSMA-based actuators on a large scale, paving the way for commercialization.