RT Journal Article
SR Electronic
T1 Organic monolayers disrupt plastic flow in metals
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP eabc8900
DO 10.1126/sciadv.abc8900
VO 6
IS 51
A1 Sugihara, Tatsuya
A1 Udupa, Anirudh
A1 Viswanathan, Koushik
A1 Davis, Jason M.
A1 Chandrasekar, Srinivasan
YR 2020
UL http://advances.sciencemag.org/content/6/51/eabc8900.abstract
AB Adsorbed films often influence mechanical behavior of surfaces, leading to well-known mechanochemical phenomena such as liquid metal embrittlement and environment-assisted cracking. Here, we demonstrate a mechanochemical phenomenon wherein adsorbed long-chain organic monolayers disrupt large-strain plastic deformation in metals. Using high-speed in situ imaging and post facto analysis, we show that the monolayers induce a ductile-to-brittle transition. Sinuous flow, characteristic of ductile metals, gives way to quasi-periodic fracture, typical of brittle materials, with 85% reduction in deformation forces. By independently varying surface energy and molecule chain length via molecular self-assembly, we argue that this “embrittlement” is driven by adsorbate-induced surface stress, as against surface energy reduction. Our observations, backed by modeling and molecular simulations, could provide a basis for explaining diverse mechanochemical phenomena in solids. The results also have implications for manufacturing processes such as machining and comminution, and wear.