Adaptive Bio-Inspired Aerospace Structures Actuated by Shape Memory Alloys

In this study, we systematically characterized the NiTiHf alloys fabricated by Selective laser Melting (SLM) process. The alloys are fabricated at University of Toledo by using selected processing parameters. University of Kentucky will characterize the shape memory and material properties. The proposed tasks are 1. Transformation Temperatures (TTs) TTs and thermal hysteresis of processed alloys are determined by using DSC. 2. Microstructure Optical microscopy and SEM are utilized to characterize the microstructure of the alloys. Grain size, amount and shape of melting pools and second phases are revealed. T 3. Superelasticity Tests The samples are loaded and then unloaded at constant temperatures above Ms. If sample doesn't recover after unloading, it is heated to (Af+50 ?C) to determine the irrecoverable strain. Critical stress for phase transformation (or variant reorientation), transformation strain, stress hysteresis, Young's modulus of mutually transforming phases will be determined as a function of temperature.