Dynamic micro-compression of dewetted intermetallic microparticles: A case study on B2-iron aluminides
This project aims to develop a micromechanical metrology technique based on thin film deposition and dewetting to rapidly assess the dynamic thermomechanical behavior of multicomponent alloys. This technique can guide the alloy design process faster than the traditional approach of fabrication of small-scale test samples using FIB milling and subsequent mechanical testing. As a case study for validation, B2-FeAl intermetallic particles are tested at a variety of strain rates and are planned to be tested at high temperatures.
The primary research in the materials community has been geared towards developing cost-effective and sustainable alloys from abundantly available cheaper material resources. The design of new alloys also requires a quick assessment of their strength at extreme conditions relevant to actual service periods, such as high strain rates–mimicking different manufacturing processes (e.g., forging) or impacts/drops. However, due to the lack of well-established high throughput mechanical testing available at extreme conditions, quick modification in the alloy design process is limited either by the cost-effective mass fabrication of test samples or the testing technique itself. To close this gap and provide more sustainable alternatives, we present the case study on iron aluminide (B2-FeAl), wherein the solid-state dewetting process is used to fabricate single-crystal intermetallic FeAl microparticles from thin films. It was observed that dewetting of FeAl films on sapphire at different annealing times leads to the formation of microparticles with different orientations, compositions, and shapes. Subsequently, the micro-compression in the strain rate range of 0.01-1000 s-1, performed using a custom-modified high-strain rate micromechanical testing setup, showed characteristic dislocation nucleation events in the stress-strain curves. The results obtained in this study shed light on both the thermal stability of Fe-Al thin films and the rate-dependent mechanical behavior of single crystalline B2-FeAl microparticles.
