Engineer’s Guide to Refractory Metal Powders

Table of Contents

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 powders

Refractory Metal Powder Compositions

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

AlloyMajor Alloying Elements
Tungsten Heavy AlloyW, Ni, Cu, Fe
Molybdenum TZMMo, Ti, Zr
TantalumTa

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:

AlloyDensity**Tensile Strength **Test Method
Tungsten Heavy Alloy18 g/cc550 MPaASTM E8
Molybdenum TZM10.2 g/cc485 MPaASTM E8
Tantalum16.6 g/cc207 MPaASTM E8

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:

Size RangeTypical MeshCommon Printing Range
Fine-325 mesh15-45 microns
Standard-100 mesh149 microns
Coarse-60 +100 mesh250 microns

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:

ParameterHigh Quality PowderEntry-level Powder
MorphologyHighly sphericalJagged, irregular
Flow RateHall flow > 35s for 50gHall flow < 25s for 50g
Apparent Density> 90% true densityOften <80% true density
Moisture Content<0.01%>0.02%

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:

Order VolumePrice Estimate
10 kg$450+/kg
100 kg$275+/kg
500+ kg$200+/kg
1000+ kgSubkey discounts
  • 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

AlloyMelting PointOxidation Resistance
Tungsten Heavy Alloy1400°CExcellent
Molybdenum TZM2600°CExcellent
Tantalum2996°CExtreme

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

AdvantagesDisadvantages
Refractory Metal PowderComplex geometriesHigher cost
Excellent high temperature strengthPost-processing
Weight reductionParameter optimization
Refractory Metal SolidLower costShape limits
AvailabilityVery heavy
MachinabilityMaterial waste

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.

refractory metal powders
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FAQs

Table 8 – Common questions:

FAQAnswer
Should I review test reports?Yes, validate certification data indicates powder quality
What size powder particles should I use?15-45 microns balances resolution and flow
What impacts consistency?Production method affects variability – vacuum melted is best
How much should I buy initially?Start small, buy more once process is validated

Table 9 – Application-focused advice:

FAQAnswer
How do I optimize for rocket nozzle components?Use extra fine <10 micron W or Mo powders to print sub 2mm channels
Which post processing approach lowers porosity?Hot isostatic pressing with inert atmosphere protects against oxidation
Which refractory alloy maximizes creep resistance?Consider additions of potassium, silicon and boron in tungsten heavy alloys based on operating temperatures
How should I adjust parameters for ultra fine feature resolution?Slow down scan speeds, increase hatch spacing, use smallest layer thicknesses machine allows

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