The University of North Texas, Denton, announces that its engineers are developing a new class of transformative complex concentrated alloys (CCAs) that can reach high levels of interfacial strengthening. Prof. Rajiv S. Mishra discussed the alloys in a presentation he prepared for the ASM International AeroMat 2020 conference that was cancelled in May.
Complex concentrated alloys (CCAs) extend the compositional paradigm shift of high entropy alloys (HEAs) to new microstructural opportunities. A new class of transformative CCAs are emerging that take advantage of phase metastability to create exceptional levels of interfacial strengthening through deformation-induced transformation and twinning. Stainless Fe-Mn-Co-Cr-Si alloys exhibit potential for this combination of phase transformation and twinning.
These alloys give greater flexibility for tailoring transformation-induced plasticity (TRIP) and twinning-induced plasticity (TWIP), which have guided design of next-generation steel alloys over the last 20 years to a new level. For TRIP CCAs, the ductility can be extended to as high as 50% while maintaining a strength exceeding 1 GPa. The Fe-Mn-Co-Cr-Si alloys show extensive gamma (fcc) to epsilon (hcp) phase transformation, followed by additional twinning in the epsilon phase.
Design of non-equiatomic CCAs provides a vast, and vastly unexplored compositional space for developing new alloys with tunable properties. Key opportunities for enhanced fatigue limit in TRIP CCAs were presented.
Exceptional strength-ductility combinations in new stainless transformative high entropy alloys
Prof. Rajiv S. Mishra, University of North Texas, Denton
