Engineer’s Guide to Refractory Metal Powders

Refractory metal powders enable additive manufacturing of extremely heat resistant alloys unmatched by other materials. This guide covers refractory powder compositions, particle specifications, properties data, pricing, and comparisons to inform procurement decisions.

Introduction to Refractory Metal Powders

Key capabilities offered by refractory powders include:

• Withstand extremely high temperatures
• Retain high strength at temperature extremes
• Resist creep deformation and cracking

Common alloys used are:

• Tungsten heavy alloys like W-Ni-Cu
• Molybdenum TZM alloy
• Tantalum powders

This guide provides considerations when selecting refractory powders:

• Alloy Compositions and Production Methods
• Mechanical Properties Test Data
• Particle Size Distribution Recommendations
• Morphology, Density and Flow Characteristics
• Pricing Estimates Based on Order Volumes
• Oxidation and Corrosion Resistance Comparisons
• Pros vs Cons Relative to Solid Forms
• FAQs on Printing Parameter Optimization

Refractory Metal Powder Compositions

Table 1 shows refractory metal powder compositions by primary elemental additions with some variation depending on alloy variant:

Small additions of carbon, potassium, silicon and boron also stabilize microstructures and grain sizes tailored for high temperature creep resistance depending on operating conditions.

Mechanical Properties and Test Methods

Table 2 shows typical minimum mechanical properties met by refractory metal powder alloys, with actual values varying based on build geometry, post-processing, and heat treatment:

Carefully validate delivered powder lot properties against certifications through sampling to ensure consistency.

Refractory Metal Particle Size Recommendations

Table 3 shows common particle size distributions used for quality refractory powders:

Other important powder characteristics:

• Spherical particle morphology
• Good flow rates exceeding 30s hall funnel time
• Apparent density within 5% of true density
• Low oxygen and moisture content

Balance high powder flowability against print resolution needs through particle size selection and distribution.

Powder Morphology, Density and Flow Properties

Table 4 compares powder characteristics between general quality levels that impact print process robustness:

Poor powder properties require extensive parameter adjustments to achieve print quality, reducing productivity.

Refractory Metal Powder Pricing

Table 5 outlines rough refractory powder pricing under normal market conditions:

• Premium alloys command higher baseline pricing
• Bulk orders beyond 500 kg enable >40% price reductions
• Actual market prices tied to commodity indexes
• Carefully validate true yields vs usable fractions from suppliers

Oxidation and Corrosion Resistance Properties

Refractory metal powders offer extremely high melting points and stability in oxidizing environments:

Table 6

Properties derive from high chromium, aluminum and silicon content creating tenacious oxide barriers preventing material loss even at extreme temperatures nearing melting points.

Pros vs Cons: Powder vs Solid Forms

Table 7

In general, refractory powders justify premiums for low volume complex components where thermal resistance is vital. Standard mill product forms offer affordability for simple shapes in high quantities.

Combining supply forms strategically reduces overall program costs.

FAQs

Table 8 – Common questions:

Table 9 – Application-focused advice:

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