Nickel Alloy Oxidation Resistance Additive Manufacturing
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Solution Overview
Problem
Current alloys for gas turbine components face challenges in achieving a balance between mechanical strength, oxidation resistance, and processability, particularly in additive manufacturing techniques, with existing materials either lacking sufficient oxidation resistance or being difficult to process.
Innovation Solution
A novel nickel-based alloy with specific compositions of elements such as Fe, Al, Cr, W, Ta, Hf, C, B, Zr, and Si, optimized for high oxidation resistance and thermal mechanical fatigue strength, while maintaining good hot cracking resistance and weldability, allowing for efficient additive manufacturing processes like selective laser melting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high Al-content alloys are used to improve oxidation resistance, then oxidation resistance is improved, but weldability and processability deteriorate due to hot cracking during additive manufacturing
Solution Approach 1:
The patent modifies the chemical composition parameters by limiting Al to 5-10 wt% (avoiding excessive Al that causes hot cracking) while optimizing other elements: Cr (10-20 wt%) for oxidation resistance, W (2-6 wt%) and Ta (2-6 wt%) for high-temperature strength, Hf (0.5-2 wt%) for grain boundary strengthening, and B (0.01-0.05 wt%) for hot cracking resistance. This parameter optimization resolves the contradiction between oxidation resistance and weldability.
Solution Approach 2:
The patent creates a composite alloy system combining multiple elements with synergistic effects: Ni-based matrix provides ductility, Al and Cr form protective oxide layers, W and Ta provide precipitation hardening, Hf strengthens grain boundaries, and B reduces hot cracking. This multi-element composite approach achieves both oxidation resistance and processability.
2Reliability
If oxidation resistant alloys are used for gas turbine components, then oxidation resistance is improved, but mechanical strength and thermal mechanical fatigue resistance deteriorate
Solution Approach 1:
The patent optimizes composition parameters to balance oxidation resistance and mechanical strength: Al (5-10 wt%) for oxide formation, Cr (10-20 wt%) for protective scale, W (2-6 wt%) and Ta (2-6 wt%) for γ' precipitation hardening, and Hf (0.5-2 wt%) for grain boundary strengthening. This compositional optimization ensures both oxidation resistance and thermal mechanical fatigue strength.
3Ease of manufacture
If conventional alloys are used for additive manufacturing, then processability is maintained, but oxidation resistance on edge regions and wear-prone areas is insufficient
Solution Approach 1:
The patent modifies conventional alloy compositions by optimizing Cr to 10-20 wt% (higher than conventional) for superior oxidation resistance, while maintaining Al at 5-10 wt% for processability, and adding Hf (0.5-2 wt%) and B (0.01-0.05 wt%) to enhance both oxidation resistance and hot cracking resistance during additive manufacturing.
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 alloy provides superior mechanical and thermal mechanical properties with enhanced oxidation resistance and processability, comparable to IN738LC, while avoiding hot cracking and maintaining structural integrity during solidification.
Implementation Method 1
A method of selective laser melting is described in EP 2 601 006 B 1, for example.
Implementation Method 2
During the manufacture, said laser beam scans over the surface and melts the powder on selected areas which may be predetermined by a CAD-file according to the geometry of the component to be manufactured.
Implementation Method 3
Currently there is the demand to provide a material, advantageously an alloy, with high oxidation resistance, particularly on regions of the respective (gas turbine) component which are highly prone to wear or abrasion during operation
Data Source
AI summary
A nickel base super alloy or blade alloy having Ni as a main constituent and the following elements or portions in wt %: Fe: 2 to 8, Al: 6.1 to 6.8, Cr: 12.5 to 15, W: 1.5 to 4.5, Ta: 2.5 to 5.5, Hf: 1.2 to 2, C: 0.03 to 0.13, B: 0.005 to 0.02, Zr: 0.005 to 0.02, and Si: 0.005 to 0.02.