Internal stress-induced melting below melting temperature at high-rate laser heating

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2014-01-01
Authors
Hwang, Yong
Levitas, Valery
Levitas, Valery
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Aerospace Engineering
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Ames Laboratory
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Mechanical Engineering
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Aerospace EngineeringAmes LaboratoryMechanical EngineeringMaterials Science and Engineering
Abstract

In this Letter, continuum thermodynamic and phase field approaches (PFAs) predicted internal stress-induced reduction in melting temperature for laser-irradiated heating of a nanolayer. Internal stresses appear due to thermal strain under constrained conditions and completely relax during melting, producing an additional thermodynamic driving force for melting. Thermodynamic melting temperature for Al reduces from 933.67 K for a stress-free condition down to 898.1 K for uniaxial strain and to 920.8 K for plane strain. Our PFA simulations demonstrated barrierless surface-induced melt nucleation below these temperatures and propagation of two solid-melt interfaces toward each other at the temperatures very close to the corresponding predicted thermodynamic equilibrium temperatures for the heating rate Q≤1.51×1010K/s" role="presentation" style="display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px 2px 0px 0px; margin: 0px; position: relative;">Q≤1.51×1010K/sQ≤1.51×1010K/s. At higher heating rates, kinetic superheating competes with a reduction in melting temperature and melting under uniaxial strain occurs at 902.1 K for Q = 1.51 × 1011 K/s and 936.9 K for Q = 1.46 × 1012 K/s.

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This article is published as Hwang, Yong Seok, and Valery I. Levitas. "Internal stress-induced melting below melting temperature at high-rate laser heating." Applied Physics Letters 104, no. 26 (2014): 263106. doi: 10.1063/1.4886799. Posted with permission.

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