|About this Abstract
||1st World Congress on High Entropy Alloys (HEA 2019)
||High Entropy Alloys 2019
||Local Plasticity and Interfacial Effects in Cubic HEA Studied by Correlative Methods
||Vaclav Ocelik, Indranil Basu, Jeff De Hosson
|On-Site Speaker (Planned)
Nanoindentation, phase analysis, EBSD and local stress analysis were applied on AlCoCrFeNi HEA. Microstructure comprises strain-free fcc phase and strongly deformed bcc phase. bcc grains shows microstructure after spinodal decomposition, alternating of ordered Ni and Al rich B2 phase and disordered Cr rich A2 phase. Indentation in the bcc grain revealed strain bursts occurring in random and stochastic manners. The observed plastic behavior was associated with dislocation hardening arising from a combination of the spinodally modulated microstructure and order hardening. Certain indents revealed a strain induced transition from bcc to fcc.
The geometry of bcc-fcc interface governs an appearance of additional yield excursions during nanoindentation near interface boundary. bcc-fcc boundary strengthening of the order of 4 GPa was estimated. The influence of image forces due to presence of a bcc-fcc interface is quantified and correlated to the measured stress and hardness gradients in both bcc and fcc grains.