We use ab initio calculations to analyze the influence of 4d and 5d transition metal alloying elements on cohesive properties of the bulk and a representative grain boundary in Cr within the framework of the Rice-Thomson-Wang approach. The results obtained for Cr are combined with the analogous results for Ni to select Ta and Nb as promising alloying additions to dual-phase ( / ) Cr-Ni-base high-temperature alloys. Ta and Nb are added to the alloying system of an existing alloy I (Cr-Ni-W-V-Ti) in an attempt to design a chemical composition of a new alloy II (Cr-Ni-W-V-Ti) + (Ta-Nb). Investigation of the microstructure of the Ta-bearing Cr-Ni-alloy reveals a Ta enrichment of large -areas near GBs in -matrix that we consider as potency to increase the cohesive strength of GBs and the cohesive energy of the bulk in -phase. Mechanical testing of alloys I and II demonstrates that the alloy II has improved tensile strength and creep resistance at high temperatures.

View the article online for updates and enhancements. Related contentForming patterns and mechanical properties of austenitic chromium-nickel steel due to strain aging N V Kamyshanchenko, V V Krasilnikov, I S Nikulin et al. A thermodynamic analysis of a multicomponent system of the Cr-Ni alloy (Cr-32Ni-1,5W-0,25V-0,5Ti) with small additions of refractory metals was carried out. The microstructure and phase composition of the base alloy (I) and alloy with additional alloying (II) were studied. The effect of additives on the mechanical properties of the Cr-Ni alloy at 20, 900 and 1080 °С was shown. The microstructure of alloys I and II was studied in the fracture zone of samples after tensile tests at different temperatures. We studied the effect of small additives on the microstructure of alloys and changes in the morphology of the structural components (phases) as a function of temperature and degree of deformation. IntroductionDevelopment and improvement of hot-strength and heat-resistant materials is one of the key issues of metal science. The use of new modern materials is a necessary condition for achieving the required tactical, technical and operational characteristics of material for space application. Extreme operating conditions of products are forced to tighten the requirements to the level and stability of the properties for materials being developed [1]. High-temperature chromium-based alloys due to significant high-temperature strength at temperatures above 1000 °C, thermal stability and high corrosion resistance are promising substitutes for nickel alloys for aerospace and power engineering application [2].At present, high-temperature Сr-based alloys has a limited employing in industry. The known alloy Cr-(31-35) Ni (1-3) W-(0.1-0.4) V-(0.05-0.3) Ti mass. % used to manufacture fuel decomposition chambers and nozzle of satellite's thrusters that operate in an impulse power setting.However, from the point of view of the ongoing update of the requirements to mechanical properties and high-temperature strength, particularly, the potential of the existing alloy is almost exhausted and its further improvement is required.The grain boundaries are the "weakest" elements of the structure in polycrystalline alloys in terms of creep resistance and a tendency to embrittlement. It is known that the properties of grain boundaries depend on their chemical composition that differs from the average chemical composition of the alloy due to segregation phenomenon [3]. Low-alloying is a well-known hardening method at which the structure and properties of alloys are changed due to local formation on borders of grains and sub-grains of the strengthening phases with limited solubility in α-γ solid solutions of alloy. The specific state of