An analysis of ductile failure by grain boundary void growth

Void growth and morphology evolution in fcc bi-crystals are investigated using crystal plasticity fi?nite element method. For that purpose, representative volume element of bi-crystals with a void at the grain boundary are considered in the analysis. Grain boundary is assumed initially perpendicular/coaxial with the straight sides of the cell. Fully periodic boundary conditions are prescribed in the representative volume element and macroscopic stress triaxiality and Lode parameter are kept constant during the whole deformation process. Three di?erent pairs of crystal orientations characterized as hard-hard, soft-soft and soft-hard has been employed for modellingthe mechanical response of the bi-crystal. Simulations are performed to study the implications of triaxiality, Lode parameter and crystallographic orientation on slip mechanism, hardening and hence void evolution. The impact of void presence and its growth on the heterogeneity of lattice rotation and resulting grain fragmentation in neighbouring areas is also analysed and discussed.

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The evaluation of microstructure, grain boundary character and micro texture of [Al/Si3N4/Al2O3] P nanocomposites fabricated through PM route and its influence on compressive and three-body wear properties

Materials Research Express ◽

10.1088/2053-1591/ac406b ◽

2021 ◽

Author(s):

Pradeep Kothiyal ◽

Amit Joshi ◽

K KS Mer ◽

Raviraj Verma

Keyword(s):

Grain Boundary ◽

Failure Mechanism ◽

Mixed Mode ◽

Research Work ◽

Ductile Failure ◽

Wear Properties ◽

Boundary Character ◽

Grain Boundary Character ◽

Grain Boundary Pinning ◽

Three Body

Abstract The compressive properties and 3 body wear characteristics of powder metallurgical (PM) processed [Al/Si3N4/Al2O3] P Nanocomposites with single and combined reinforcement of Al2O3 and Si3N4 reinforcing particles having different compositions (1%, 2% and 3%) were studied and evolution of microstructure, grain boundary character and micro texture of fabricated [Al/Si3N4/Al2O3] P Nanocomposites was investigated through EBSD in the present research work. The fraction of high angle boundaries (HAGBs) were observed more in combined reinforcing samples of Al2O3 and Si3N4 whereas a single reinforcing sample of Al2O3 and Si3N4 showed fewer HAGBs. Micro texture results showed the strong textures components near to {112}<111> Cu and {110}<111 for pure sintered Al sample P and mixed reinforcement composites (M1, M2 and M3) > P whereas for single reinforcing sample showed weak textures near to transverse direction. Out of all fabricated composites, 2 % mixed Al2O3 and Si3N4 reinforced composite revealed the maximum ultimate compressive strength (209.98 MPa) and least wear rate (0.1 mm3/min mm3/N-cm for 1 kg load and 3.5 mm3/N-cm for 2kg load) attributing formation of nanocluster causing grain boundary pinning effect. The dominant failure mechanism for all samples was also detected and found to be a mixed-mode ductile failure mechanism for 2 % mixed Al2O3 and Si3N4 reinforcement composite while other sample failed through ductile as well as mixed-mode mechanisms.

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