Theoretical investigation on yttrium clustering in tungsten grain boundary region and strengthening effect

Abstract

We have systematically investigated the solution and aggregation behaviors of yttrium (Y) on symmetrically inclined tungsten (W) grain boundary (GB) [Formula: see text](310)/[001] by first-principles simulation. It is found that the most stable site for Y is located on the GB plane, and the solution energy of the Y substitutional site increases with increasing the distance from the GB plane. The charge redistribution of Y atoms is positively correlated with the solution energy, i.e., the deviation of the electrons of Y atoms is beneficial to its solution in the W–GB system. Further, the segregation of multiple Y atoms in the W–GB is clearly observed, where the Y atoms preferentially occupy the GB plane substitutional sites. The alloying Y atoms at the GB plane sites can effectively strengthen the GB when the concentration is less than 3.367%. The stronger binding energy of W–Y than the binding energy of W–W in the GB region is the main factor for the strengthening of the GB.

The Effect of Yttrium on the Solution and Diffusion Behaviors of Helium in Tungsten: First-Principles Simulations

“…Previous works indicate that the improvement of mechanical properties can be achieved by grain refinement [ 8 , 9 , 10 ]. For example, alloying Y could improve the mechanical properties of W [ 11 , 12 ]. Y plays an important role in affinity oxygen of W, significantly reducing the damage caused by oxygen [ 13 ].…”