Local chemical ordering coordinated thermal stability of nanograined high-entropy alloys

Nanograined(NG)materials often suffer from low thermal stability owing to the high volume fraction of grain boundaries(GBs).Herein,we investigate the possibility of utilizing local chemical ordering(LCO)for improving the thermal stability of NG FeCoNiCrMn highentropy alloys(HE As).NG HE As with two different grain sizes were considered.Tensile tests and creep test simulations were then performed to reveal the influence of LCO on the mechanical properties and thermal stability of NG HE As.After performing hybrid molecular dynamics and Monte Carlo simulations,Cr atoms were found to accumulate at GBs.By analyzing the atomic structure evolution during the deformation process,we found that the formation of LCO effectively stabilized the GBs and inhibited GB movement.In addition,dislocation nucleation from GBs and dislocation movement was also hindered.The inhibiting effect of LCO on GB movement and dislocation activity is more prominent than in the NG model with smaller grain sizes.The current simulation results suggest a possible strategy for enhancing the thermal stability of NG HEAs for service in a high-temperature environment.

Application of phase-field modeling in solid-state phase transformation of steels

Solid-state phase transformation is usually associated with excellent mechanical properties in steel materials.A deep understanding of the formation and evolution of phase structure is essential to tailor their service performance.As a powerful tool for capturing the evolution of complex microstructures,phase-field simulation quantitatively calculates the phase structures evolution without explicit assumptions about transient microstructures.With the development of advanced numerical technology and computing ability,phase-field methods have been successfully applied to solid-state phase transformation in steels and greatly support the research and development of advanced steel materials.The phase-field simulations of solid-phase transformation in steels were summarized,and the future development was proposed.

Research status and prospect of direct strip casting manufactured lowcarbon microalloyed steel

Direct strip casting(DSC)is one of the cutting-edge technologies for the steel industry in the twenty-first century.Under the background of carbon peak and carbon neutrality,DSC technology has a bright future of applications as it requires less production time and space with reduced energy consumption.Owing to its sub-rapid cooling rate during solidification and low reduction during hot rolling,DSC process exhibits a series of unique physical metallurgy characteristics.The process characteristics of DSC process and the microstructural evolution during the thermomechanical processing of low-carbon microalloyed steel are reviewed.The effects of hot rolling,cooling,coiling temperatures and microalloying elements on the microstructure and mechanical properties are then discussed.Finally,the future development orientations of DSC technology are suggested to fully utilize its unique features for the enhancement of its competitiveness and for the promotion of carbon neutrality of the steel industry.