Diffusion Bonding Alloy Surface Preparation to Suppress Secondary Phases
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Solution Overview
Problem
Existing diffusion bonding methods form secondary phases such as Ti-rich carbides or Al-rich oxides at the interface, limiting grain boundary migration and reducing mechanical properties at both room and high temperatures.
Innovation Solution
A method involving a coating step with a nickel alloy precursor, a surface alloying step to mix base material and precursor elements, and a polishing step to remove impurities, promoting grain boundary migration and suppressing secondary phase formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diffusion bonding is performed using conventional methods, then bonding is achieved, but secondary phases form at the interface limiting grain boundary migration and reducing mechanical properties
Solution Approach 1:
The patent applies preliminary action by performing surface treatment (shot blasting, sand blasting, or grit blasting) on the alloy surfaces before diffusion bonding. This preliminary surface roughening creates anchoring effects and increases surface area, preventing the formation of planar grain boundaries that would limit grain boundary migration. The surface treatment is performed in advance to eliminate the harmful effect of secondary phase formation at the interface, thereby improving mechanical properties without requiring filler materials.
2Stability of the object's composition
If filler metal is inserted to promote grain boundary migration, then grain boundary migration is enhanced, but diffusion-induced grain boundary migration occurs due to chemical composition gradient
Solution Approach 1:
The patent extracts and eliminates the need for filler metal by using surface treatment methods (shot blasting, sand blasting, or grit blasting) on the base alloy surfaces. This removes the source of chemical composition gradients that cause diffusion-induced grain boundary migration. The surface treatment creates physical anchoring effects without introducing foreign elements, thereby promoting healthy grain boundary migration without the harmful effects associated with filler metal insertion.
3Shape
If secondary phases are formed at the diffusion bonding interface, then bonding structure is created, but grain boundary migration is limited across the interface
Solution Approach 1:
The patent applies preliminary surface treatment (shot blasting, sand blasting, or grit blasting) before diffusion bonding to create a roughened surface morphology. This preliminary action prevents the formation of planar grain boundaries at the interface, thereby enabling grain boundary migration without being constrained by secondary phase formations. The surface treatment is performed in advance to establish favorable grain boundary conditions that promote migration while maintaining compositional stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method enhances mechanical properties of the diffusion bonding member to match those of the base material at room and high temperatures by forming a grain boundary migration region and minimizing secondary phases.
Implementation Method 1
a surface alloying step of forming an alloying region by mixing the base material and constituent elements of the alloy precursor layer
Implementation Method 2
a polishing step of preparing an alloy surface for diffusion bonding by removing at least a portion of the alloying region
Implementation Method 3
diffusion bonding is one method of solid bonding, and it is a technique that connects materials by using the thermal diffusion of atoms at high temperatures
Data Source
AI summary
The present invention relates to a method for preparing an alloy for diffusion bonding, comprising a matrix and an alloyed region having a different chemical composition from the matrix, and the method may comprise: (a) a coating step of forming an alloy precursor layer containing nickel (Ni) on the surface of a base material; (b) a surface alloying step of forming an alloyed region by mixing the base material and constituent elements of the alloy precursor layer, and (c) a polishing step of preparing an alloy surface for diffusion bonding by removing at least a portion of the alloyed region.