Al含量对FeV50合金相变的影响及机理研究

Effects of Al Content on Phase Transformation in FeV50 Alloy and Its Mechanism

对不同Al含量的FeV50进行熔化和随炉冷却试验,用X射线衍射(XRD),扫描电镜(SEM)分析检测物相和微观组织,结果表明:FeV50合金随Al含量的增加,其室温物相由单一的σ相逐渐向α相转变;Al含量存在临界值0.8%,低于0.8%时,FeV50为σ相,超过0.8%,将出现两相共存直至转变为单一的α相。分析认为Al对FeV50合金相变的影响机理表现在两个方面:①随Al含量的增加,合金液的临界晶核尺寸逐渐变大,使得体系中没有过多的能量作为α→σ相变的驱动力;②Al含量越高,其对Fe原子扩散的抑制作用越强,Fe的同素异构转变不能进行,从而阻止α→σ相变的发生。

FeV50 alloys with different Al contents were furnace, then their phases and microstructures were inve smelted and cooled to room temperature inthe stigated by X-ray diffraction（XRD） and scanning electron microscope （SEM）respectively. The results showed that with the increase of Al content in FeV50, the phase transformation from σ phase to α phase was found. The 0.8% Al content was so critica1 that when it was below 0.8%, FeV50 was in form of o＂ phase, but when above 0.8% two phases co- existed until a single α phase was obtained. It is supposed that Al affects the phase transformation in two ways. First, critical nucleus size becomes larger with the increase of Al which resuhs in less energy available as driving force for α→σ phase transformation in the system. Second, the higher Al content , the stronger its inhibitory effect on the Fe atom diffusion, and as a result allotropic transformation of Fe is prevented, thus, α→σ phase transformation is retarded.