Platinum Group Metal Containing High Entropy Alloys for High Temperature Applications

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Metals such as platinum, palladium, iridium, osmium, rhodium and ruthenium (collectively known as the platinum group metals, or PGMs) have a number of unusual and attractive properties, including resistance to chemical attack and high temperature environments. They are however also relatively scarce and high cost (platinum is actually among the least expensive of these elements). Johnson Matthey supplies specialised PGM alloys to the automotive and aerospace sectors for ignition, forming key parts of common components such as spark plugs, as well as in more advanced applications. The alloys work extremely well for this purpose; however, customers are continually seeking more cost effective solutions.We will look at the physical metallurgy of PGMs and use this understanding to develop alternative alloys with equivalent or better performance, but lower PGM content. To achieve this the work will focus on a novel alloying strategy of multi principal component alloys (also called High Entropy Alloys), which are known to show unexpected behaviours in other systems. Such alloys have yet to be explored in the PGMs, although research on refractory alloys more generally indicates that complex systems may exhibit interesting properties. The project will involve work on both predictive methods and experimental validation.