脉冲电子束改性TC4钛合金微观组织和性能

Microstructure and property of TC4 titanium alloy by pulsed electron beam modification

采用低能强电流(LEHC)脉冲改性技术处理TC4钛合金表面,利用扫描电子显微(SEM)、场发射扫描电镜(FESEM)、透射电子显微(TEM)和纳米压痕分析(NI)等方法对表面改性层组织进行表征,按照不同低能强电流脉冲改性工艺下改性层的组织特征,结合纳米压痕硬度试验,分析了脉冲电子束改性晶粒的细化机制。结果表明,脉冲电子束改性试样可分为熔化相变层、热影响层和基体三个区域;熔化相变层中的晶粒细化机制是脉冲电子束改性时随着温度的快速升高,表面层发生熔化后的重新结晶以及α相在β相中的析出;晶粒细化是表层纳米压痕硬度提高的主要原因。

TC4 titanium alloy was treated by pulsed electron beam with low energy and high current（LEHC）.Microstructure and property of the modified alloy were investigated by means of scanning electron microscopy（SEM）,field emission electron microscopy（FEEM）,transmission electron microscopy（TEM）,and nano-indention（NI） methods.The grain refinement mechanism was discussed based on hardness measurement in the modified layer.The results show that the modified layer consists of melted zone and heat affect zone on substrate.In the process of pulsed electron beam modification,melting,crystallization and phase transformation occur in surface layer of the alloy and fine microstructure of α and β phases forms.The increase of hardness in modified layer is due to grain refinement.