Effect of Alloying Elements and Impurity (N) on Bulk and Grain Boundary Cohesion in Cr-Base Alloys

Abstract

Effect of comprehensive alloying system (W, Ta, Nb, Mo, V, Hf, Ti, Zr, Ni) and impurity N on cohesive properties of the bulk and the special high-angle grain boundary (GB) Σ5 (210)[100] in Cr-base alloys, as well as segregation behavior of impurities at the GB and the (210) free surface are studied by first principles calculations. The analysis of the data obtained allows us to single out W, Ta as the best and nitrogen as the worst interatomic bond strengthening elements for both the bulk and GB in Cr-base alloys. To verify these theoretical results by means of experiment, we investigated an influence of W (up to 10 wt. %), and (Ta, Nb, Hf and Zr) on mechanical properties of Cr-base alloy. We observed an increasing of the strength properties due to W addition and increasing of the plasticity as a result of (Ta, Nb, Hf, Zr) adding.

Effect of а Number of Transition Metals on the Cohesive Properties of Cr-Ni-Base Alloys

“…In our previous study [16], we have shown that some of the "low alloying" elements that improve cohesive properties of Ni-base phase have a negative effect on the GB strengthening (η) of Cr-base phase (Zr, Hf, Nb, see line Cr-base). However, this fact is partly related to extremely high cohesive properties of Cr itself [17] and given that all of the selected alloying elements improve the bulk cohesion of Cr, alloying of our test alloy with Zr, Hf, Nb and Ta should not alter much the cohesive strength of the Cr-base phase.…”