Indium (In) whisker growth from MAB phase Ti2InB2

Ti 2 InB 2 , a typical member of MAB phases (a family of layered transition metal borides), has gained wide attention due to its excellent properties. However, in this work, Ti 2 InB 2 is found to share a similar A-site metal whisker growth phenomenon with MAX phases (a family of layered carbides/nitrides), which casts doubt on its reliability, and therefore would hinder its applications in advanced technologies. Specifically, the weaker bond between Ti and In atoms in Ti 2 InB 2 leads to the exfoliation of In atomic layers under mechanical damage. It is proposed that the In atoms released by the mechanochemically decomposed Ti 2 InB 2 have high chemical potentials and are inclined to crystallize, which is responsible for the In whisker growth. Furthermore, it is observed that the decomposition degree of Ti 2 InB 2 affects the whisker growth propensity and morphology. Understanding the In whisker growth mechanism is meaningful to ensure the reliability as Ti 2 InB 2 is finding technological applications.