Ti70Nb7.8Cu8.4Ni7.2Al6.6复合材料
(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)
摘 要: 采用机械合金化制备不含和含2%(体积分数)B4C的钛基非晶合金粉末,随后采用放电等离子烧结−非晶晶化法合成不含/含(TiB+TiC)的Ti70Nb7.8Cu8.4Ni7.2Al6.6超细晶/细晶钛基复合材料;运用X射线衍射分析(XRD)、差示扫描量热分析(DSC)、扫描电子显微镜(SEM)和万能材料试验机等对制备的钛基非晶粉末和超细晶/细晶钛基复合材料进行表征。结果表明:高能球磨80 h的钛基粉末中主要为非晶相,B4C颗粒的加入对钛基粉末的玻璃转变温度、晶化温度和晶化焓有显著的影响。另外,不含/含(TiB+TiC)的复合材料的显微硬度分别为5.47和5.33 GPa;以50 K/min升温到1 223 K并保温10 min获得的Ti70Nb7.8Cu8.4Ni7.2Al6.6块体试样的断裂强度和断裂应变分别为2 098 MPa和11.5%。
关键字: 钛基复合材料;放电等离子烧结;机械合金化;晶化
(National Engineering Research Center of Near-net-shape Forming for Metallic Materials,
South China University of Technology, Guangzhou 510640, China)
Abstract:The Ti-based amorphous alloy powders without or with 2% (volume fraction, %) B4C were synthesized by mechanical alloying, and subsequently the powders were consolidated into crystallized Ti70Nb7.8Cu8.4Ni7.2Al6.6 ultrafine/fine-grained composites without or with (TiB+TiC) phases by spark plasma sintering and crystallization of amorphous phase. The synthesized powders and the consolidated ultrafine/fine-grained composites were examined by X-ray diffractometry (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and universal materials tester. The results show that, after a milling time of 80 h, the synthesized powders consist of amorphous phase with predominant volume fraction. The addition of B4C particles has an obvious impact on the glass transition temperature, crystallization temperature and crystallization enthalpy for the synthesized powders. In addition, the microhardnesses of the consolidated composites without or with 2% B4C are 5.47 and 5.33 GPa, respectively. Meanwhile, the consolidated Ti70Nb7.8Cu8.4Ni7.2Al6.6 composite by heating to 1 223 K at 50 K/min and holding for 10 min has a high fracture strength of 2 098 MPa and a fracture strain of 11.5%.
Key words: Ti-based composite; spark plasma sintering; mechanical alloying; crystallization