Microstructure and High-Temperature Strength of Fe-Al-Si(-Mo) Alloys with Refractory Metal Additives

The study investigates the microstructure and high-temperature strength of Fe-Al-Si(-Mo) alloys, which are potential materials for high-temperature applications. The objective is to analyze the effects of multi-alloying with silicon, molybdenum, and vanadium/tungsten on mechanical strength at elevated temperatures. Using compression tests, the research evaluates the contributions of various strengthening mechanisms during high-temperature deformation. Findings indicate that the addition of vanadium or tungsten significantly enhances yield stress values, particularly in the 700–800°C temperature range. Moreover, the influence of heat treatment on both the microstructure and yield stress values is assessed. Long-term annealing at 800°C results in a slight decline in yield stress for both alloys due to the precipitation of secondary phase particles; however, the yield stress reduction is partially mitigated by strengthening from fine incoherent precipitates in the Fe28Al5Si2Mo1W alloy. Short-term annealing at 1200°C leads to peak yield stress values across the temperature range for both tested alloys, attributed to the formation of new phase nuclei, which are confirmed through prolonged annealing time. This comprehensive analysis enhances the understanding of alloy performance in high-temperature environments.