Abstract
TiB crystal whiskers (TiBw) can be synthesized in situ in Ti alloy matrix through powder metallurgy for the preparation of a new type of ceramic fiber-reinforced Ti matrix composite (TMC) TiBw/Ti-6Al-4V. In the TiBw/Ti-6Al-4V TMC, the reinforced phase/matrix interface is clean and has superior comprehensive mechanical properties, but its machinability is degraded. Hence, the bonding of reliable materials is important. To further optimize the TiBw/Ti-6Al-4V brazing technology and determine the relationship between the microstructure and tensile property of the brazed joint, results demonstrate that the elements of brazing filler metal are under sufficient and uniform diffusion, the microstructure is the typical Widmanstätten structure, and fine granular compounds in β phase are observed. The average tensile strength of the brazing specimen is 998 MPa under room temperature, which is 97.3% of that of the base metal. During the high-temperature (400 °C) tensile process, a fracture occurred at the base metal of the highest tensile test specimen with strength reaching 689 MPa, and the tensile fracture involved a combination of intergranular and transgranular modes at both room temperature and 400 °C. The fracture surface has dimples, secondary cracks are generated by the fracture of TiB whiskers, and large holes form when whole TiB whiskers are removed. The proposed algorithm provides evidence for promoting the application of TiBw/Ti-6Al-4V TMCs in practical production.
Highlights
The reinforcement of titanium matrix composites (TMCs) with ceramic phase results in superior wear resistance and specific strength [1,2,3]
The microstructure and elemental diffusion of the TiB crystal whiskers (TiBw) /Ti-6Al-4V brazed joint were analyzed
Based on pervious results obtained by other scholars [12,13,14]; normally, the brazed joints include two parts: fusion zone (FZ) and diffusion zone (DZ)
Summary
The reinforcement of titanium matrix composites (TMCs) with ceramic phase results in superior wear resistance and specific strength [1,2,3]. In comparison with the traditional TMCs reinforced by ceramic particles and fibers, the bonding performance at the interface between reinforced phase TiB and matrix is better in TiBw /Ti-6Al-4V [4], and the mechanical properties are not anisotropic [5]. High-performance TiBw /Ti-6Al-4V can be used as a substitute for some existing Ti alloys in various fields, such as aerospace, communication technology, and precision instrument manufacturing [6]. The addition of ceramic phase with extremely high hardness degrades the plasticity of TMCs and elevates the requirements for preparation conditions; it complicates the one-time formation of this kind of material, restricting the application of TMCs in the manufacturing of large complex structures [7]
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