Transient Liquid Phase Diffusion Bonding
Transient liquid phase diffusion bonding is a diffusion process where a thin melting phase briefly melts and solidifies isothermally. It enables stable joints without artifacts.
Physicochemical Mechanism of Action
Transient liquid phase diffusion bonding (TLPDB) is based on the short-term melting of a thin interlayer between the materials being joined. This melt phase forms through temperature and pressure, allowing atoms from both metals to exchange. After the melt phase, the system cools isothermally, which leads to crystallization and stabilization of the new joint.
Metallurgical Relevance & Welding Risks
TLPDB allows high toughness and a fine-grained structure in the weld. It reduces the occurrence of cracks and hardness peaks, since the joint is made without strong melting of the metals. A risk, however, is that wrong temperature control or too short a cooling time can lead to incomplete diffusion, which causes faulty joints and possible cracks.
Workshop Practice & Instructions
For successful TLPDB it is crucial to ensure correct temperature and pressure control. The melt phase should be melted briefly (about 1-2 seconds), followed by isothermal cooling over a certain time (depending on the material, typically 5-10 seconds). This ensures homogeneous diffusion and a stable joint without artifacts.