The Effect of Temperature on Interfacial Gradient Plasticity in Metallic Thin Films
The Effect of Temperature on Interfacial Gradient Plasticity in Metallic Thin Films
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温度对金属薄膜界面梯度塑性的影响
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
D. Faghihi
中科院分区：
文献类型：
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作者：
G. Voyiadjis;D. Faghihi
当介质的表面积与体积比增加时，例如在微米和纳米系统中，材料微结构界面对尺度相关的屈服强度和应变硬化具有深远的影响。本文采用考虑界面能效应的高阶应变梯度塑性理论框架，研究了小尺度快速瞬态过程中材料的热力耦合响应。除了非局部屈服条件的材料散装，温度和速率相关的微观屈服条件的接口，它确定的应力时，接口开始塑性变形和硬化。为了解决强化和硬化机制，该理论的基础上开发的机械状态变量分解成能量和耗散对应物。这就使得本构方程分别具有能量和耗散梯度长度尺度（ell _{en}）和（ell _{dis}）。因此，四个材料长度尺度的介绍：两个为散装和其他两个接口。此外，温度对屈服强度和界面硬化的影响包括在配方中，通过假设界面能随着温度的升高而降低。最后，对所建立的框架进行了数值求解，研究了薄膜-衬底系统非轴向载荷的尺寸效应。
The material microstructural interfaces have a profound impact on the scale-dependent yield strength and strain hardening when the surface-to-volume ratio of the medium increases such as in micro and nanosystems. In this paper, the framework of higher-order strain gradient plasticity with interfacial energy effect is used to investigate the coupling of thermal and mechanical responses of materials in small scales and fast transient processes. In addition to the nonlocal yield condition for the material bulk, a temperature and rate dependent microscopic yield condition for the interface is presented, which determines the stress at which the interface begins to deform plastically and harden. In order to address the strengthening and hardening mechanisms, the theory is developed based on the decomposition of the mechanical state variables into energetic and dissipative counterparts. This, consecutively, provides the constitutive equations to have both energetic and dissipative gradient length scales (ell _{en}) and (ell _{dis}) respectively. Hence four material length scales are introduced: two for the bulk and the other two for the interface. In addition, the effect of temperature on the yield strength and hardening of the interface is included in the formulation by postulating that the interfacial energy decreases as temperature increases. Finally the developed framework is solved numerically to investigate the size effect of unaxial loading of a film substrate system.