Microstructure and mechanical properties of V–Me(Cr,W)–Zr alloys as a function of their chemical–thermal treatment modes

Abstract

a b s t r a c tFormation of regularities of the nanometric oxide precipitates and defect microstructure in vanadium-based low activation alloys V-Cr-Zr-(C,N,O) and V-Cr-W-Zr-(C,N,O) as a function of the regimes of their thermochemical treatment was investigated. Several methods of internal oxidation which provide formation of the nanosized ZrO 2 particles of controllable dispersion, ensure the nanometric size of the heterophase structure to be maintained up to the temperatures as high as 1300-1400°С, and allow the recrystallization temperature to be increased up to ≥1400°С were proposed. Formation of such microstructure contributes to dispersionand substructural hardening and results in more than twofold increase in the yield stress of these alloys both at room and elevated (800°С) temperatures, compared to the conventional thermo-mechanical treatment.

Structure and Phase Composition of a W-Ta-Mo-Nb-V-Cr-Zr-Ti Alloy Obtained by Ball Milling and Spark Plasma Sintering

“…In [49], stabilization of cubic zirconia in the form of nano-sized particles was observed in V-based alloys dispersion-strengthened by internal oxidation. The presence of dispersed particles causes increased short-term high-temperature strength and improved high-temperature phase stability of the alloy.…”

Increasing the Thermal Stability and High-Temperature Strength of Vanadium Alloys by Strengthening with Nanosized Non-Metallic Particles

“…CHT with the method of nonequilibrium internal oxidation, similarly to the works in [ 25 , 32 , 33 ], consisted of two stages: (1) formation of a surface scale during annealing in air at 650 °C for 5 to 30 min; and (2) vacuum annealing with a total duration of 9 h, with a stepwise increase in temperature from 620 to 1000 °C, to transfer oxygen from the surface scale into the sample.…”

“…The authors of the works in [ 25 , 32 ] proposed vanadium alloys of the V–Me(Cr, W)–Zr–C system with purposeful alloying with interstitial (C, N, O) and substitutional (W, Zr) elements. The main phase-forming element of the alloys of such a system is Zr, which is characterized by a high chemical activity towards interstitial impurities (C, N, O).…”