Diffusion Bonding of Ti 6242 to γ -TiAl Alloys

摘要

The Ti-6242 alloys are chosen for aero-engine applications due to high temperature strength and creep resistance that are achieved through microstructural tailoring of alloys. The new class of light weight materials, γ-TiAl base intermetallics are considered candidate materials to replace the current materials in service at high temperatures. Both materials are well studied for processing, characterisation and structural applications. However, fully utilisation of these materials for demanding engineering applications necessitate advanced joining technologies where homogeneous material properties are retained with high deformation and crack resistant joints. The present paper reports on a systematic study of diffusion bonding process of α/β Ti-6242Si and γ-TiAl intermetallic alloys. Emphasis is put on the optimisation of joining process parameters for industrial applications, followed by characterisation and properties of the diffusion bond joints. The process variables temperature, pressure and time are optimised to produce joints with sound structure, bond quality and strength. The chemical composition and phase morphology are studied using scanning electron microscopy and energy dispersive X-ray (EDX) analysis. Micro-tensile tests at ambient to high temperatures were carried out for mechanical characterisation, and deformation and fracture studies.