Surface-Stress Induced Embrittlement of Metals
Surface-Stress Induced Embrittlement of Metals
复制标题
金属表面应力引起的脆化
DOI：
10.1021/acs.nanolett.1c02887
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发表时间：
2021
期刊：
影响因子：
10.8
通讯作者：
Chandrasekar, Srinivasan
中科院分区：
文献类型：
--
作者：
Udupa, Anirudh;Sugihara, Tatsuya;Viswanathan, Koushik;Latanision, Ronald M.;Chandrasekar, Srinivasan
金属中的环境辅助断裂现象通常与表面能因吸附薄膜而降低有关。在这里，我们展示了一种独特的铝的脆化效应，它是由吸附的有机单分子膜引起的表面应力所介导的。原子模拟表明，吸附碳链的长度通过范德华作用力控制表面应力，作用力为压缩作用力，反之为拉伸作用力。对于lc>；8，我们在实验上证明了纳米薄膜在宏观尺度上引起了从延性到脆性的转变。伴随这一转变的是变形力减少了近85%。进一步的模拟表明，脆化的微观机制是通过抑制初始裂纹尖端的位错发射来实现的。除了挑战长期以来关于环境辅助断裂的观点外，我们关于表面应力引起的脆化的发现还表明，在机械加工和粉碎等制造过程中具有有益的实用价值。
Environment-assisted fracture phenomena in metals are usually associated with surface energy reduction due to an adsorbed film. Here we demonstrate a unique embrittlement effect in Al that is instead mediated by surface stress, induced by an adsorbed organic monolayer. Atomistic simulations show that the adsorbate carbon-chain lengthlccontrols the surface stress via van der Waals forces, being compressive forlc< 8 and tensile otherwise. Forlc> 8, we demonstrate experimentally that the nanoscale film causes a ductile-to-brittle transition on the macroscale. Concomitant with this transition is a nearly 85% reduction in deformation forces. Additional simulations reveal that the microscopic mechanism for the embrittlement is via suppression of dislocation emission at incipient crack-tips. In addition to challenging long-held views on environment-assisted fracture, our findings pertaining to surface-stress induced embrittlement suggest profitable utility in manufacturing processes such as machining and comminution.