Effects of grain boundary density and temperature on thermal conductivity of Fe-10%Cr alloys with [001] tilt boundaries: An atomistic study

The objective of this study is to examine the effects of grain boundary (GB) density and temperature on lattice thermal conductivity of Fe-10%Cr alloys containing different [001] tilt GBs. The effects of three different [001] tilt boundaries (e.g., 5-310-13510, and 17530) of various densities have been examined at sixteen different temperatures between 10 K to 400 K using the reverse non-equilibrium molecular dynamics (rNEMD) simulation technique. The results reveal that Fe-Cr models with -17-530-GB exhibit a higher conductivity than the models with other two types of GBs at all temperatures. The GBs are found to impose a resistance to the heat flow that causes a sharp temperature drop across the boundaries. Below 120 K, the conductivity exhibits an inverse relationship with GB density, however above 120 K the effect of GB density becomes insignificant. The conductivity values are found to be higher at a lower temperature, e.g., at 10 K, and decreases with temperature. The variation of with temperature shows three distinct regions: (i) between 10-90 K, decreases steadily with temperature; (ii) between 90-120 K, a sudden drop in conductivity is observed; and (iii) above 120 K, becomes independent of temperature.