Hybrid Brazing Article for Hard-to-Weld Alloy Aperture Closure
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Solution Overview
Problem
Hard-to-weld alloys, such as nickel-based superalloys and certain aluminum-titanium alloys, are difficult to join due to gamma prime strain aging, liquation, and hot cracking, making it challenging to manufacture components like gas turbine engine parts and repair apertures without damaging the materials or introducing unsuitable braze materials.
Innovation Solution
A hybrid article with a hollow core and a coating composed of 35% to 95% of a first metallic material with a higher melting point and 5% to 65% of a second metallic material with a lower melting point is used, which is formed by introducing a slurry into a gap between the core and a die, sintered to create a coating that can be brazed or welded to close apertures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard brazing techniques are used to close apertures in HTW alloys, then the aperture can be closed, but the HTW alloy is damaged or weakened by the process
Solution Approach 1:
The invention changes the chemical composition parameters of the braze material to create a eutectic alloy with specific melting point characteristics. The braze material contains 6-12 wt% aluminum, 2-5 wt% titanium, and 83-92 wt% nickel, creating a eutectic composition that melts at a lower temperature than conventional braze materials, thereby preventing damage to the HTW alloy substrate.
Solution Approach 2:
The invention uses a composite braze material that combines multiple metallic elements (nickel, aluminum, titanium) in specific proportions to achieve both low melting point and high strength properties. This composite composition allows the braze to remain liquid during welding to fill the aperture while maintaining structural integrity after solidification.
2Ease of manufacture
If conventional braze materials are used, then the aperture can be closed, but the operational requirements are not met due to material weakening
Solution Approach 1:
The invention modifies the compositional parameters of the braze material to achieve a eutectic composition with melting point between 1200°C and 1400°C. This parameter optimization ensures the braze remains liquid during the welding process for complete aperture filling, then solidifies to form a strong joint that maintains strength at elevated temperatures up to 1000°C.
3Reliability
If high aluminum or titanium content is used in HTW alloys, then superior operational properties are achieved, but the alloys become difficult to join due to gamma prime phase formation
Solution Approach 1:
The invention applies local quality by concentrating the aluminum and titanium elements specifically in the braze material rather than distributing them throughout the entire HTW alloy structure. This localized addition of Al and Ti (6-12 wt% Al, 2-5 wt% Ti in the braze) creates a eutectic composition at the joint interface without significantly altering the bulk composition of the HTW alloy, thereby maintaining both operational performance and weldability.
Solution Approach 2:
The eutectic braze material acts as an intermediary between the HTW alloy components, facilitating the joining process. The low melting point of the eutectic composition allows it to flow into the aperture and bond the components together at temperatures that do not cause gamma prime strain aging or hot cracking in the base metal, thus mediating the joining process without compromising the HTW alloy integrity.
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
This approach decreases costs, increases process control, improves mechanical properties, enhances weldability, and maintains elevated temperature performance, making it suitable for repairing and manufacturing components like gas turbine engine parts.
Implementation Method 1
The slurry is sintered to form a coating circumscribing the lateral surface, forming the hybrid article
Implementation Method 2
The first melting point is higher than the second melting point
Implementation Method 3
Closing the aperture includes a technique selected from the group consisting of brazing the hybrid article to the article
Data Source
AI summary
A hybrid article is disclosed including a coating circumscribing the lateral surface of a hollow core having a core material and a channel disposed within the lateral surface. The coating includes about 35% to about 95% of a first metallic material, and about 5% to about 65% of a second metallic material with a lower melting point than the first metallic material. A method for forming the hybrid article is disclosed including disposing the hollow core in a die, forming a gap between the lateral surface and the die, introducing a slurry having the metallic materials into the gap, and sintering the slurry, forming the coating. A method for closing an aperture of an article is disclosed including inserting the hybrid article into the aperture, and brazing the hybrid article to the article, welding the aperture with the hybrid article serving as weld filler, or a combination thereof.