PT  - JOURNAL ARTICLE
AU  - Sugihara, Tatsuya
AU  - Udupa, Anirudh
AU  - Viswanathan, Koushik
AU  - Davis, Jason M.
AU  - Chandrasekar, Srinivasan
TI  - Organic monolayers disrupt plastic flow in metals
AID  - 10.1126/sciadv.abc8900
DP  - 2020 Dec 01
TA  - Science Advances
PG  - eabc8900
VI  - 6
IP  - 51
4099  - http://advances.sciencemag.org/content/6/51/eabc8900.short
4100  - http://advances.sciencemag.org/content/6/51/eabc8900.full
SO  - Sci Adv2020 Dec 01; 6
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.