TC4/ZrO_2复合材料激光近净成形微观组织分析

Microstructure Analysis of TC4/ZrO_2 Composites Formed by Laser Engineered Net Shaping

采用激光近净成形系统成形了不同ZrO_2掺入量的TC4/ZrO_2薄壁,研究了扫描速率对金属基陶瓷材料成形热应力的影响,利用X射线衍射仪(XRD)、扫描电镜(SEM)、X射线能量色散谱仪(EDS)对薄壁样件进行相组成分析、微观组织观察以及元素分布检测。研究表明,相对较低的扫描速度可以减小薄壁件的残余应力,抑制样件的宏观裂纹;XRD结果显示当ZrO_2含量达到30%以上时,生成了TiO.325的Ti的非化学计量氧化物;TC4基体的微观组织随着ZrO_2掺入量的增多晶粒逐渐从针状过渡到板条状、块状;EDS结果显示当Ti晶粒为板条状,晶界间有ZrO_2富集;随着ZrO_2含量增多,Ti固溶体中固溶的Zr增多。本研究为最终成形TC4/ZrO_2梯度材料提供了可靠的技术支持。

TC4/ZrO2 composite thin-wall samples with adding different proportion of ZrO2 were produced by laser engineered net shaping The influence of scanning speed on thermal stress in forming process was studied. X-ray diffractometer （XRD）, scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS） were used for the sample phase composition analyses, microstructure observation and element distribution testing, respectively. Results indicate that lower scanning speed can reduce the residual stress of the thin-wall samples and inhibit cracking. The result of XRD shows that when the proportion of ZrO2 is higher than 30%, nonstoichiometric compound, TIO.325, is formed; the grain morphology of TC4 matrix changes from acicular, lamellar to bulk grain with the increasing of proportion of ZrO2. The result of EDS shows a segregation of ZrO2 at lamellar Ti grain boundaries; the content of Zr in Ti solid solution increases with the content of ZrO2 increasing. A reliable technical support is provided by this study to finally form TC4/ZrO2 graded materials