Université Paris Est-Laboratoire Navier, ENPC-Paris, LCPC, CNRS UMR 8205, Champs-sur-Marne, France.
Phys Rev Lett. 2010 Dec 31;105(26):266001. doi: 10.1103/PhysRevLett.105.266001. Epub 2010 Dec 20.
Extensive measurements of macroscopic stress in a 2D Lennard-Jones glass, over a broad range of temperatures (T) and strain rates (γ), demonstrate a very significant decrease of the flowing stress with T, even much below the glass transition. A detailed analysis of the interplay between loading, thermal activation, and mechanical noise leads us to propose that over a broad (γ, T) region, the effect of temperature amounts to a mere lowering of the strains at which plastic events occur, while the athermal avalanche dynamics remains essentially unperturbed. Up to the vicinity of the glass transition, temperature is then shown to correct the athermal stress by a (negative) additive contribution which presents a universal form, thus bringing support to and extending an expression proposed by Johnson and Samwer [Phys. Rev. Lett. 95, 195501 (2005)].
对二维 Lennard-Jones 玻璃进行了广泛的宏观应力测量，涵盖了很宽的温度 (T) 和应变速率 (γ) 范围，结果表明流动应力随 T 显著降低，甚至远低于玻璃转变温度。对加载、热激活和机械噪声之间相互作用的详细分析使我们提出，在很宽的 (γ, T) 区域内，温度的影响仅仅是降低了发生塑性事件的应变，而无热涨落动力学基本保持不变。直到玻璃转变附近，温度通过呈现出通用形式的（负）附加贡献来修正无热应力，从而为 Johnson 和 Samwer [Phys. Rev. Lett. 95, 195501 (2005)] 提出的表达式提供支持并加以扩展。
