H Induced Decohesion of an Al Grain Boundary Investigated with First Principles: General Conditions for Instant Breakage and Delayed Fracture
16 Pages Posted: 25 Feb 2019 First Look: Under Review
The uniaxial tensile test response of a H decorated Σ5  twist grain boundary (GB) in face-centered-cubic Al has been examined with first principles. The impurity shows a strong tendency to relocate during loading. To capture these H movements, the standard model framework was extended to probe loading-unloading hysteresis. If the maximum tensile stress accepted by the H decorated GB in the slow fracture limit is reached before the maximum acceptable strain, exceeding this stress may trigger a H influx-controlled destabilization, as opposed to 'immediate' breakage. Such 'delayed' failure appears likely whenever the H attraction to a GB displays a monotonic decrease with increased loading.
Keywords: fracture, metal grain boundary, H embrittlement, aluminum, first-principle calculation
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