Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, 34095 Montpellier, France.
Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, 34095 Montpellier, France;
Proc Natl Acad Sci U S A. 2018 Jun 26;115(26):6656-6661. doi: 10.1073/pnas.1806156115. Epub 2018 Jun 11.
We combine an analytically solvable mean-field elasto-plastic model with molecular dynamics simulations of a generic glass former to demonstrate that, depending on their preparation protocol, amorphous materials can yield in two qualitatively distinct ways. We show that well-annealed systems yield in a discontinuous brittle way, as metallic and molecular glasses do. Yielding corresponds in this case to a first-order nonequilibrium phase transition. As the degree of annealing decreases, the first-order character becomes weaker and the transition terminates in a second-order critical point in the universality class of an Ising model in a random field. For even more poorly annealed systems, yielding becomes a smooth crossover, representative of the ductile rheological behavior generically observed in foams, emulsions, and colloidal glasses. Our results show that the variety of yielding behaviors found in amorphous materials does not necessarily result from the diversity of particle interactions or microscopic dynamics but is instead unified by carefully considering the role of the initial stability of the system.
我们将一个解析可解的平均场弹塑性模型与通用玻璃形成体的分子动力学模拟相结合，证明了取决于它们的制备方案，非晶材料可能以两种截然不同的方式发生屈服。我们表明，经过良好退火的系统会以不连续的脆性方式屈服，就像金属和分子玻璃一样。在这种情况下，屈服对应于一级非平衡相变。随着退火程度的降低，一级特征变得较弱，转变在各向同性随机场伊辛模型的通用类中以二阶临界点结束。对于退火程度更低的系统，屈服变成了一个平滑的交叉，代表了泡沫、乳液和胶体玻璃中普遍观察到的韧性流变行为。我们的结果表明，非晶材料中发现的各种屈服行为不一定是由粒子相互作用或微观动力学的多样性引起的，而是通过仔细考虑系统初始稳定性的作用而统一起来的。
