Titanium Alloy Grain Refinement via Lanthanide Additives
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Solution Overview
Problem
Titanium-based alloys exhibit large grain sizes during additive manufacturing, leading to reduced strength, ductility, and fatigue properties due to the nucleation and growth of high-temperature beta phase crystals, which limits their application in critical aerospace components.
Innovation Solution
Incorporating 0.001-1.0% by weight of lanthanide series elements, such as neodymium, gadolinium, or erbium, into titanium-based alloys to disrupt the growth of large grains during solidification, resulting in a finer grain size and improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If additive manufacturing processes are used to produce titanium-based alloy components, then near net-shape capability and productivity are improved, but large grain size and coarse beta grain structure develop during solidification, worsening mechanical properties and fatigue resistance
Solution Approach 1:
The patent modifies the chemical composition parameters of the titanium alloy by adding specific elements (e.g., ruthenium at 0.01-1.0 wt%, rhodium at 0.01-0.5 wt%, or iridium at 0.01-0.1 wt%) to change the solidification behavior and grain structure characteristics, thereby improving mechanical properties while maintaining additive manufacturing capability
Solution Approach 2:
The patent creates a composite alloy system by combining titanium with trace amounts of refractory elements (ruthenium, rhodium, iridium) to achieve a refined microstructure with smaller beta grain size, resulting in a material that exhibits both improved strength and ductility for additive manufacturing applications
2Speed
If high cooling rates and high thermal gradients are applied during additive deposition, then solidification speed is improved, but large elongated grains form, worsening microstructure quality and mechanical properties
Solution Approach 1:
The patent changes the material composition parameters by incorporating specific refractory elements that modify the solidification kinetics and thermal conductivity, enabling finer grain control even under the high cooling rates and thermal gradients inherent in additive manufacturing processes
3Ease of manufacture
If coarse beta grain size forms during solidification, then solidification process is simplified, but alpha phase forms at grain boundaries, worsening elongation and ductility
Solution Approach 1:
The patent modifies the alloy composition by adding specific refractory elements that suppress alpha phase formation at grain boundaries and promote a finer, more uniform beta grain structure, thereby improving ductility and elongation while maintaining manufacturing simplicity
4Strength
If titanium-based alloys are used for aerospace components, then high strength-to-weight ratio and corrosion resistance are achieved, but high material cost and high buy-to-fly ratio worsen economic efficiency
Solution Approach 1:
The patent optimizes the alloy composition by adding only trace amounts (0.01-1.0 wt%) of expensive refractory elements like ruthenium, rhodium, or iridium, achieving significant improvements in mechanical properties and fatigue resistance while minimizing the impact on material cost and maintaining the high strength-to-weight ratio required for aerospace applications
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 addition of lanthanide series elements refines the grain size, enhancing the strength, ductility, and fatigue properties of titanium-based alloys, making them more suitable for additive manufacturing in aerospace applications.
Implementation Method 1
Titanium-based alloys exhibit solidification behavior in which crystals of high-temperature beta phase nucleate and grow to long dimensions during additive deposition processes
Data Source
AI summary
An alpha-beta titanium-based alloy including titanium; one of 0.001-1.0 wt. % neodymium, 0.001-1.0 wt. % dysprosium, or 0.001-0.5 wt. % erbium; and at least one of aluminum, zirconium, tin, oxygen, molybdenum, vanadium, niobium, iron, and chromium present in amounts defined based on an aluminum equivalent and a molybdenum equivalent, wherein the aluminum equivalent (Al-eq) is between 0 to 7.5% and the molybdenum equivalent (Mo-eq) is between 2.7 to 47.5, and wherein the aluminum equivalent (Al-eq) and the molybdenum equivalent (Mo-eq) are defined, in weight percents, as follows:Al-eq=(Al %)+(Zr %)/6+(Sn %)/3+10*(O %)Mo-eq=(Mo %)+0.67*(V %)+0.33*(Nb %)+2.9*(Fe %)+1.6*(Cr %).