A general indicator for the tolerance to impurities of metals and alloys

The tolerances of alloys to impurities can vary significantly across impurity-alloy combinations and are largely unknown beyond the most common alloys and impurities. Further, a more general framework to quantify, compare, and practically utilize the tolerance of elements and alloys to impurities is missing. Here, we propose such a framework based on the parameter CIM, the maximum content of an impurity that can be added to a pure element before it no longer crystallizes and instead vitrifies, as measured under sputtering conditions. Using high throughput combinatorial methods, CIM can be readily determined for practically important impurity-element combinations. We argue that CIM generally indicates impurity tolerance because it ubiquitously measures solid solution stability and provide arguments on how conclusions may be drawn from impurity-element to impurity-alloy tolerance. This practical metric for evaluating impurity tolerances for alloys may help metallurgy by enabling greater recycled feedstock compatibility during manufacturing and, in the future, the design of more impurity tolerant alloys.