A computational method has been developed to calculate the pressure required for grain boundaries to overcome the pinning effects of second phase particles. Multiple Pt bicrystals were constructed with small concentrations (<= 0.5 atom %) of Au segregated to the boundary using the Monte Carlo method. Molecular dynamics (MD) simulations employing the artificial driving force method were carried out on said boundaries to measure the relationship between boundary type, solute concentration, and boundary velocity. It was found that for a given solute concentration there exists a critical driving pressure necessary for grain boundary motion to occur. Sub-critical driving pressures resulted in flexing of the grain boundary about the pinning precipitates, but with no large scale grain boundary movement. Above critical driving pressures resulted in grain boundary motion although the amount of time required for grain boundaries to break loose from the pinning structures varied considerably. At solute concentrations of 0.1%, solute segregation to the boundary did not occur. The resulting lack of precipitates caused boundaries to behave no differently from pure boundaries, although at real timescales a reduction in mobility would be exhibited because of solute drag. Development of a method to quantify the effect of different solute concentrations on the stability of different grain boundaries will prove useful for understanding phenomena such as abnormal grain growth, as well as aid in the engineering of stabilized nanocrystalline alloys.
5:00 PM–7:00 PM Apr 23, 2019 (US - Arizona)
PCC North, 300 Level, Exhibit Hall C-E