Rediscovering the intrinsic mechanical properties of bulk nanocrystalline indium arsenide

Abstract

Is the inverse Hall–Petch relation in ceramic systems the same as that in metal systems? The premise to explore this subject is the synthesis of a dense bulk nanocrystalline material with clean grain boundaries. By using the reciprocating pressure-induced phase transition (RPPT) technique, compact bulk nanocrystalline indium arsenide (InAs) has been synthesized from a single crystal in a single step, while its grain size is controlled by thermal annealing. The influence of macroscopic stress or surface states on the mechanical characterization has been successfully excluded by combining first-principles calculations and experiments. Unexpectedly, nanoindentation tests show a potential inverse Hall–Petch relation in the bulk InAs with a critical grain size (D_cri) of 35.93 nm in the experimental scope. Further molecular dynamics investigation confirms the existence of the inverse Hall–Petch relation in the bulk nanocrystalline InAs with D_cri = 20.14 nm for the defective polycrystalline structure, with its D_cri significantly affected by the intragranular-defect density. The experimental and theoretical conclusions comprehensively reveal the great potential of RPPT in the synthesis and characterization of compact bulk nanocrystalline materials, which provides a novel window to rediscover their intrinsic mechanical properties, for instance, the inverse Hall–Petch relation of bulk nanocrystalline InAs.