So called high entropy alloys have garnered a lot of interest in recent years due to their non traditional alloying philosophy with no single dominant element. Initial efforts have shown that the name of this alloy class is a little misplaced and compositionally complex alloys might be a better name. Whatever their name these alloys have the potential to offer a wide range of mechanical and physical properties.
In FCC HEAs this includes uniquely high toughness at cryogenic temperatures though deformation twinning, and in BCC alloys this includes high strengths retained to higher temperatures than in traditional alloys. However if these alloys are to be used in engineering applications then a much more though understanding on how microstructure links to and controls mechanical deformation mechanisms in these alloys.
In Oxford we have worked on developing both FCC and BCC alloys and this project will use a range of macro and micro mechanical testing methods in ambient and non ambient conditions to understand deformation mechanisms in these alloys. We are particularly interested in how either low levels of impurity elements (such as carbon or nitrogen) and second phases (often Laves phases) effect deformation mechanisms. We envisage using micro-mechanical testing methods to probe individual phases and using this data to predict properties of bulk polyphase-polycrystalline materials. DIC and HR-EBSD will be used along with crystal plasticity FEA simulations to study the resulting deformation patterns at the microstructural length scale.
