成分和过冷度对亚共晶Fe-B合金的凝固速率和硬度的影响

Effect of Composition and Undercooling on the Solidification Rate and Hardness of Hypoeutectic Fe-B Alloy

为了探究成分和过冷度对亚共晶Fe-B合金的凝固速率和硬度的影响,文中采用熔融玻璃净化法和高速摄影技术,对比研究了两种成分Fe-B亚共晶合金的共晶凝固行为差异。实验结果表明,初生相和共晶相转变速率都会随形核过冷度增大而增大;但在同一形核过冷度下,硼含量增加,初生相转变速率减小,而共晶相转变速率增大。采用硬度排序法分析凝固组织的硬度发现,随凝固过冷度的增加,α-Fe相硬度值不断增加,而Fe2B相硬度值逐渐减小,并且样品整体硬度变化区间缩小。由于硬度主要决定于硼元素含量,所以样品的硼元素随着过冷度增加分布趋于均匀化。

In order to examine the effect of composition and undercooling on the solidification rate and hardness of hypoeutectic Fe-B alloy,a contrastive study is conducted of the solidification behavior of two hypoeutectic Fe-B alloys by the fluxing glass purification method and high-speed photography technology.The results show that the higher the nucleation undercooling,the greater the transformation rates of the primary phase and the eutectic phase.However,at the same undercooling,the greater the boron content,the lower the primary transformation rate and the higher the eutectic transition rate.An analysis of the microstructure hardness by the sorted method shows that,with the increase of solidification undercooling,the hardness value of theα-Fe phase increases,while the hardness of the Fe2B phase gradually decreases,with the range of hardness being smaller.Since the hardness is mainly determined by the boron content,the distribution of boron element in the sample tends to be uniform with the increase of undercooling.