Grain boundary segregation of B and microstructure evolution in a hot-drawn Fe–B alloy

Abstract

The grain boundary segregation (GBS) of boron and microstructure evolution in a hot-drawn Fe–B alloy are investigated utilising the Gleeble-1500, Auger electron spectrometer, time-of-flight secondary ion mass spectrometry, electron back-scattered diffraction, and transmission electron microscopy techniques. The results suggest substantial boron segregation at grain boundaries of the Fe–B alloy during the hot drawing process. In comparison to the contribution of dislocations to boron diffusion coefficients, the influence of vacancies is predominant. With the increase in hot-drawing temperature, the ratio of excess vacancy content to thermal equilibrium vacancy content $C_{ex}/C_{th}$ decreases, and the content of low $\sum \mathrm{CSL}$ (low Sigma coincidence site lattice) boundaries increases, resulting in a reduction in boron GBS content. Additionally, elevating the hot-drawing temperature promotes dynamic recrystallisation and refines the grains. The volume fraction of the <110>//RD (rolling direction) texture component initially increases and then decreases with increasing temperature, reaching a maximum value of 64.6% at 830 °C, while the percentage of the <100>//RD + <111>//RD texture components exhibits the opposite trend, with a peak value of 27.4% observed at 1000 °C.