Production of cast master alloys with high chromium content using centrifugal SHS metallurgy

Cast master alloys of the Mo–Cr, W–Cr, and Cr–Al systems with high chromium content were produced using the methods of centrifugal SHS metallurgy. A thermodynamic analysis was performed to evaluate the combustion temperature and the equilibrium composition of the reaction products depending on the ratios of the initial components in the mixture. Based on this analysis, optimal compositions were identified for further experimental studies. The effectiveness of functional additives, namely calcium fluoride CaF₂ (fluorspar) and sodium hexafluoroaluminate Na₃[AlF₆] (cryolite), was experimentally confirmed. These additives were shown to lower the melting point of the slag phase (reducing its viscosity), which facilitated phase separation during the production of cast master alloys from refractory metals using centrifugal SHS metallurgy. The experiments demonstrated the need to introduce excess amounts of MoO₃ and WO₃ during the production of Mo–Cr and W–Cr master alloys, respectively, due to incomplete reduction of molybdenum and tungsten from their oxides. Microstructural analysis of the obtained master alloys revealed a dendritic structure, which is typical for cast materials. EDS microanalysis showed that the chemical compositions of all synthesized alloys closely matched their calculated and target compositions. Composition analysis at different locations within the ingots revealed no significant variations in composition. X-ray phase analysis confirmed the presence of solid solution phases formed from the target elements. The results of inductively coupled plasma mass spectrometry (ICP-MS) confirmed that the chemical compositions of the synthesized Cr–W, Cr–Mo, and Cr–Al alloys fully comply with the permissible concentrations of both target elements and impurities.

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