Refractory Metal Alloy Additive Manufacturing
Solution Overview
Problem
Molybdenum and tungsten alloys face challenges in additive manufacturing due to low ductility, poor weldability, and high oxygen content leading to defects and low fracture resistance, with conventional processes being inefficient and resulting in components with intercrystalline fracture behavior and low density.
Innovation Solution
An alloy comprising refractory metals like molybdenum and tungsten with boron and optionally carbon, processed via selective laser or electron beam melting, where boron forms borides that refine the microstructure, reduce oxygen content, and enhance grain boundary strength, leading to improved mechanical properties and reduced porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional powder metallurgical processes are used to produce molybdenum and tungsten components, then manufacturing is feasible, but the components exhibit intercrystalline fracture behavior and low density
Solution Approach 1:
The invention changes the chemical composition parameters by adding boron (0.01-5 at%) and carbon (0.01-5 at%) to the refractory metal alloy. This compositional modification transforms the microstructure from coarse-grained intercrystalline to fine-grained cellular structure, achieving both high density (>95% theoretical) and transcrystalline fracture behavior with improved fracture resistance
Solution Approach 2:
The invention creates a composite microstructure consisting of refractory metal matrix with embedded borides (e.g., Mo2B, W2B) and carbides. This composite structure at the micro level provides both high density and enhanced fracture resistance by preventing intercrystalline fracture through the formation of fine cellular grains bounded by strengthening phases
2Adaptability or versatility
If beam-based additive manufacturing is used to manufacture molybdenum and tungsten components, then geometric design freedom is improved, but build rate remains very low
Solution Approach 1:
The invention modifies the alloy composition parameters to include boron and carbon, which fundamentally changes the solidification behavior and microstructure formation during additive manufacturing. This enables faster processing while maintaining geometric design freedom, as the modified composition allows for controlled cellular microstructure formation even at higher build rates
3Ease of manufacture
If high oxygen content is present in molybdenum and tungsten alloys, then conventional processing is easier, but defect formation increases and fracture resistance decreases
Solution Approach 1:
The invention converts the harmful effect of oxygen by introducing boron and carbon elements that have higher affinity for oxygen. These elements form stable oxides and borides, effectively removing free oxygen that would cause defects. The boron and carbon thus act as oxygen getters, transforming oxygen from a harmful impurity into beneficial oxide/boride phases that strengthen the alloy
Solution Approach 2:
The invention introduces boron and carbon as intermediary elements that mediate between oxygen and the refractory metal matrix. These intermediaries preferentially bond with oxygen to form stable compounds (borides, carbides, and oxides), preventing oxygen from causing direct harm to the alloy structure and instead creating strengthening phases at grain boundaries
4Temperature
If molybdenum and tungsten are used for high-performance applications, then high melting point and thermal conductivity are achieved, but ductility at room temperature and weldability are poor
Solution Approach 1:
The invention creates a composite alloy system combining refractory metals (Mo, W) with boron and carbon. This composite composition produces a fine cellular microstructure with grain boundary strengthening phases that significantly improve ductility and weldability while preserving the high melting point and thermal conductivity of the base refractory metals
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 approach results in components with high relative density, transcrystalline fracture behavior, and increased flexural strength, significantly improving ductility and fracture resistance by creating a fine-grained cellular microstructure and binding oxygen, thus overcoming the limitations of prior art.
Implementation Method 1
selective laser beam melting (SLM) and selective electron beam melting (SEBM), in which powder applied layer-wise is locally melted
Implementation Method 2
selective laser beam melting (SLM) and selective electron beam melting (SEBM), in which powder applied layer-wise is locally melted
Implementation Method 3
the mechanisms of action in processes comprising local melting and solidification at high cooling rate
Implementation Method 4
heat flow, heat flow direction and internal stresses as a result of solidification shrinkage
Data Source
AI summary
A component having a solid structure of an alloy which, as a main component, contains a refractory metal (RM) from the group of molybdenum and tungsten and, as a further component, boron (B) and optionally carbon (C). The solid structure is manufactured additively by laser beam or electron beam, and the solid structure has regions made of the RM or a mixed crystal of the RM and the regions are at least partially delimited by (RM)2B, where B in (RM)2B can be partially replaced by C.