Search results
Results From The WOW.Com Content Network
Micrograph of a polycrystalline metal; grain boundaries evidenced by acid etching. Differently-oriented crystallites in a polycrystalline material. In materials science, a grain boundary is the interface between two grains, or crystallites, in a polycrystalline material.
A model of grain boundary diffusion developed by JC Fisher in 1953. This solution can then be modeled via a modified differential solution to Fick's Second Law that adds a term for sideflow out of the boundary, given by the equation + (,) = ′, where ′ is the diffusion coefficient, is the boundary width, and (,) is the rate of sideflow.
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 sort of partitioning of solute atoms between the grain boundary and the lattice was predicted by McLean in 1957. [3] Non-equilibrium segregation, first theorized by Westbrook in 1964, [4] occurs as a result of solutes coupling to vacancies which are moving to grain boundary sources or sinks during quenching or application of stress. It can ...
Grain boundary sliding is the process by which grains move to prevent separation at grain boundaries. [1] This process typically occurs on timescales significantly faster than that of mass diffusion (an order of magnitude quicker). Because of this, the rate of grain boundary sliding is typically irrelevant to determining material processes.
Zener pinning is the influence of a dispersion of fine particles on the movement of low- and high-angle grain boundaries through a polycrystalline material. Small particles act to prevent the motion of such boundaries by exerting a pinning pressure which counteracts the driving force pushing the boundaries.
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.
In materials that were deformed under very high temperatures, lobate grain boundaries may be taken as evidence for diffusion creep. [7] Diffusion creep is a mechanism by which the volume of the crystals can increase. Larger grain sizes can be a sign that diffusion creep was more effective in a crystalline material.