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In materials science, a grain boundary is the interface between two grains, or crystallites, in a polycrystalline material. Grain boundaries are two-dimensional defects in the crystal structure, and tend to decrease the electrical and thermal conductivity of the material.
Figure 1: Hall–Petch strengthening is limited by the size of dislocations. Once the grain size reaches about 10 nanometres (3.9 × 10 −7 in), grain boundaries start to slide. In materials science, grain-boundary strengthening (or Hall–Petch strengthening) is a method of strengthening materials by changing their average crystallite (grain
This is also known as intercrystalline fracture or grain-boundary separation. More rapid diffusion along grain boundaries than along grain interiors; Faster nucleation and growth of precipitates at the grain boundaries; Quench cracking, or crack growth following a quenching process, is another example of intergranular fracture and almost always ...
This material exhibits an ultra-high hardness, higher than any reported ultrafine-grained nickel. The exceptional strength is resulted from the appearance of low-angle grain boundaries, which have low-energy states efficient for enhancing structure stability. Another method to stabilize grain boundaries is the addition of nonmetallic impurities.
Grain boundary sliding (GBS) is a material deformation mechanism where grains slide against each other. This occurs in polycrystalline material under external stress at high homologous temperature (above ~0.4 [1]) and low strain rate and is intertwined with creep.
This toughening becomes noticeable when there is a narrow size distribution of particles that are appropriately sized. Researchers typically accept the findings of Faber's analysis, which suggest that deflection effects in materials with roughly equiaxial grains may increase the fracture toughness by about twice the grain boundary value.
Cleavage separations: [1] cleavage planes are the weaknesses in crystals. Therefore, stresses are likely to be concentrated on these weakness planes first. [1] Microcracking from stress concentrations at grain boundaries: [1] the contacts between grain boundaries provide space for stresses to be concentrated, especially tensile stresses. [1]
Intergranular corrosion is generally considered to be caused by the segregation of impurities at the grain boundaries or by enrichment or depletion of one of the alloying elements in the grain boundary areas. Thus in certain aluminium alloys, small amounts of iron have been shown to segregate in the grain boundaries and cause intergranular ...