钢/铜/钛扩散复合界面显微组织和力学性能

Microstructure and Mechanical Properties of Diffusion Bonded Joints Between Carbon Steel and Titanium with Copper Interlayer

采用碳钢管作为基层、纯钛管作为覆层、纯铜箔作为中间层,利用拉拔-内压热扩散复合法,制备碳钢、铜、钛三金属管复合管.借助扫描电镜(SEM)观察了复合界面附近的显微组织并用能谱分析仪(EDS)测定了界面附近的元素分布.通过剪切和硬度试验测定了界面剪切强度及其附近的显微硬度.研究扩散温度和时间工艺因素对界面附近组织和剪切强度的影响.结果表明:扩散退火后,界面结合紧密,无明显缝隙;钛/铜界面的强度随保温时间增加而有所提高,铜/钢界面强度有所降低;铜、钛原子互扩散至对方基体中,使基体组织、硬度发生改变,并在铜、钛界面上形成了TiCu、TiCu2、βTiCu4化合物;扩散时间对剪切强度的影响有一限度,扩散时间超过限度时,剪切强度降低.

Diffusion bonded trimetallic tube was prepared by a drawn and internal pressure diffused method with pure titanium and carbon steel as base metals and pure copper as a interlayer. The microstructures near the interfaces were observed using optical and scanning electron microscopes （ SEM）, and the elemental distribution across the interfaces was determined by energy dispersive spectroscopy. Shear strength and microhardness were obtained using shearing and Vickers hardness tests. The results show that the interfaces are bonded firmly with no visible fissure or void after diffusion annealed; the interface strength of the titanium/copper is increased with the increase in holding time, while the interface strength of the copper/steel is decreased slightly, matrix microstructure and hardness changed with the diffusion of Ti and Cu. The reaction products are TiCu, TiCu2 and βTiCu4 form near the interface due to Cu and Ti atomic interdiffusion. A margin exists in the effect of diffusion time on interface shear strength which decreases beyond the margin.