Ti66Nb18Cu6.4Ni6.1Al3.5细晶复合材料
(1. 华南理工大学 国家金属材料近净成形工程技术研究中心，广州 510640；
2. 内蒙古第一机械制造(集团)有限公司 车辆工程研究院，包头 014030)
摘 要: 基于改进的非晶形成合金体系，选取Ti66Nb18Cu6.4Ni6.1Al3.5合金为研究对象，通过放电等离子烧结机械合金化制备的非晶合金粉末，结合非晶晶化法，合成以高Nb含量的晶化β-Ti(Nb)延性相为基体的块状细晶复合材料。利用X射线衍射(XRD)、差示扫描量热仪(DSC)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和万能材料试验机等手段对合成的非晶合金粉末和细晶复合材料进行表征分析。结果表明：球磨60 h后，初始混合粉末绝大部分转变成了非晶相，其玻璃转变温度、晶化温度、晶化峰值温度和熔化温度分别为750 K、830 K、847 K和1422 K，表明Nb含量的增加显著提高合金体系的热稳定性。另外，合成的块状钛基细晶复合材料的显微结构为β-Ti延性相包围(Cu, Ni)-Ti2相，其相区尺寸均大于1 μm。当升温速率为167 K/min、烧结温度为1 373 K时，合成的复合材料密度、屈服强度、断裂强度和断裂应变分别为5.64 g/cm3、1 705.8 MPa、2 126.4 MPa和5.4%。
关键字: 非晶复合材料；机械合金化；放电等离子烧结；晶化
（1. National Engineering Research Center of Near-net-shape Forming for Metallic Materials,
South China University of Technology, Guangzhou 510640, China;
2. Automobile Engineering Academy, Inner Mongolia First Machinery Group Corporation, Baotou 014030, China）
Abstract:Ti66Nb18Cu6.4Ni6.1Al3.5 alloy system was selected as the study object based on modified amorphous alloy system. The bulk Ti66Nb18Cu6.4Ni6.1Al3.5 fine grained composites with matrix of crystallized β-Ti(Nb) ductile phase were fabricated by spark plasma sintering of mechanical alloyed amorphous alloy powders coupled with the method of crystallization of amorphous phase. X-ray diffractometer (XRD), differential scanning calorimeter (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and universal materials tester were employed to investigate the alloyed amorphous powders and the fabricated composites. The results show that the initial mixed powders are predominately alloyed into amorphous structure after milling for 60 h. The crystallization temperature (Tx), crystallization peak temperature (Tp) and melting point (Tm) of the alloyed amorphous powders are 750 K, 830 K, 847 K and 1 422 K, respectively. This indicates that the increased Nb content enhances significantly the thermal stability of alloyed powders. In addition, the fabricated composites has a microstructure of (Cu, Ni)-Ti2 phase surrounded by ductile β-Ti phase. The scale of the two phase regions is above 1 μm. Under a heating rate of 167 K/min and a sintering temperature of 1 373 K, the fabricated composite has a density of 5.64 g/cm3, a yield stress of 1 705.8 MPa, a fracture stress of 2 126.4 MPa and a fracture strain of 5.4%.
Key words: amorphous alloy composite; mechanical alloying; spark plasma sintering; crystallization
