Aluminium Alloy Powder

Table of Contents

Aluminium alloy powder refers to powder metallurgy forms of aluminium alloys. Aluminium powders find use in various applications due to their lightweight, high strength, corrosion resistance, thermal conductivity, and electrical conductivity.

Overview of Aluminium Alloy Powder

Aluminium alloy powder is produced by atomization of molten alloys into fine droplets which solidify into powder particles. The composition and properties of the alloy powder can be tailored based on requirements.

Key details about aluminium alloy powder:

  • Produced by atomization of aluminium alloys into fine powder
  • Particle size ranges from few microns to millimeters
  • Spherical, irregular, or flake particle shapes
  • Variety of alloying elements used – Si, Mg, Zn, Cu etc.
  • Properties dependent on alloy composition
  • Lightweight, high strength, corrosion resistance
  • Used for additive manufacturing, thermal spray, MIM etc.

Aluminium Alloy Powder Types

TypeCompositionCharacteristics
Pure Al99%+ AlLow strength, high electrical conductivity
1000 seriesAl + Mn, Fe, SiWork-hardenable, higher strength
2000 seriesAl-CuHeat treatable, high strength
5000 seriesAl-MgModerate to high strength
6000 seriesAl-Mg-SiMedium to high strength
7000 seriesAl-ZnHighest strength
aluminium alloy powder

Aluminium Alloy Powder Composition

Aluminium alloy powders contain aluminium as the base metal along with alloying elements. Some common alloy additions include:

  • Silicon – improves castability and welding characteristics
  • Magnesium – increases strength through precipitation hardening
  • Copper – highest strengthening effect, but reduces corrosion resistance
  • Zinc – enhances strength through precipitation hardening
  • Manganese – increases strength without reducing ductility
  • Chromium – improves high temperature strength
  • Zirconium – grain structure refiner giving uniform properties

Exact composition is specified by 4 digit numerical designations defined in various international standards.

Aluminium Alloy Powder Properties

PropertyDescription
StrengthVaries from low to very high strength depending on alloy type and condition
DensityAround 2.7 g/cm3, making it much lighter than steels
Electrical conductivityHigh but less than pure aluminium, varies by alloy
Thermal conductivityHigh but alloying additions reduce it from pure Al value
Corrosion resistanceGenerally good due to protective oxide layer but varies by alloy composition
WeldabilityTypically good but some alloys can lose strength
WorkabilitySofter low alloy powders allow extensive forming
CostHigher than steel powder but more economical than titanium

Aluminium Alloy Powder Characteristics

ParameterDetails
Particle shapeSpherical, irregular, flakes
Particle sizeFrom 1 micron to 1000 micron
Size distributionVaries from tight distributions to wide ranges
Apparent densityAround 2.5 g/cm3
Tap densityAround 2.7 g/cm3
Flow rateImportant for powder handling and processing
CompressibilityDetermines final part density achieved

Aluminium Alloy Powder Applications

Aluminium alloy powders find usage across various industries due to their beneficial properties:

ApplicationDetails
Additive manufacturingUsed in powder bed fusion and directed energy deposition
Metal injection molding (MIM)Low cost high volume production of complex parts
Thermal spray coatingsProvide wear and corrosion protection for components
Powder forgingProduces net shape blanks for downstream processing
WeldingAdded to provide alloying elements for weld filler metal
PyrotechnicsFine reactive powders used to produce effects or gas
BrazingUsed as filler material to join aluminium components

Additive Manufacturing Using Aluminium Alloy Powder

Additive manufacturing techniques like selective laser melting (SLM), direct metal laser sintering (DMLS) and electron beam melting (EBM) use aluminium alloy powder feedstock to produce end-use components across aerospace, automotive and industrial sectors.

Some benefits of AM with Al alloy powder:

  • Complex geometries not possible by conventional methods
  • Reduced weight through optimized designs
  • Part consolidation improves manufacturing efficiency
  • Properties comparable to wrought products in most alloys
  • Minimal material wastage compared to subtractive techniques

Current limitations in AM using Al powder include:

  • High reflectivity demands higher power lasers
  • High thermal conductivity makes heat control difficult
  • Cost is higher compared to conventional techniques for production volumes
  • Porosity control and anisotropic properties remain a challenge
  • Surface finish quality currently inferior to machined parts
  • Restricted alloy choice compared to wrought alloys

Ongoing process developments continue to improve quality, capabilities and economics of additively manufactured aluminium components.

Metal Injection Molding with Aluminium Alloy Powder

Metal injection molding (MIM) can produce complex, tight tolerance, net-shape metallic components using aluminium alloy powder feedstock at relatively low costs.

Benefits of MIM with aluminium alloy powder:

  • Intricate parts with walls and features < 0.5 mm
  • Tight dimensional tolerances approaching +/- 0.1%
  • As-sintered properties similar to PM or cast alloys
  • Near full density and good surface finish
  • Automated high volume production possible

Limitations for MIM using aluminium powders:

  • More difficult to process than steel and harder tooling needed
  • Higher melting point increases molding machine demands
  • Reactivity limits binder choices for feedstock formulation
  • Secondary finishing may be needed to achieve final properties

Despite challenges, MIM continues to expand into high performance sectors due to advantages over other manufacturing approaches for complex aluminium alloy components.

Aluminium Alloy Powder for Thermal Spray

Aluminium alloy powders like AA2024, AA5083 and AA7075 are commonly used as feedstock material for various thermal spray coating processes to protect components against wear, corrosion, heat etc.

ProcessDescription
Combustion Wire-arcTwo wire arc metalizing process with simple equipment
Flame sprayingPowder injected into oxygen-fuel gas flame
High Velocity Oxy-Fuel (HVOF)High kinetic energy spray minimizing porosity
Cold sprayingSolid state deposition via high speed powder impact
Plasma sprayingMost versatile technique with hot ionized gas

Benefits of using Al alloy powder for thermal spray coatings:

  • Provides wear and corrosion protection
  • Restores oversized parts to original dimensions
  • Minimal heat input prevents substrate warpage
  • As-sprayed coatings or with infiltration for full density
  • Lower material costs than high alloy weld overlays
  • Simpler processing than many wrought alloys

Aluminium Alloy Powder Specifications

Aluminium alloy powders are produced according to various standard specifications that define the acceptable composition limits, particle size ranges, shape control etc.

StandardDescription
AMS 4200Aerospace material specification for atomized Al alloy powder
ASTM B602Standard specification for Al alloy powders
EN 1706European standard specification for atomized Al powders
ISO 13318International standard for gas and water atomized Al powders
DIN 50125German national standard for atomized Al powders

Specifications allow customers to procure powder suitable for their specific application and process requirements.

Sizes of Aluminium Alloy Powder

Various size ranges of aluminium alloy powder are produced depending on end use:

  • Ultrafine powder < 10 microns for reactive applications
  • Fine powder 15 – 45 microns commonly for thermal spray
  • Medium powder 45 – 100 microns widely used size
  • Coarse powder up to 150 microns for specialty applications

Larger particles over 180 microns mainly used in cold spray processes for thicker coatings. Control of particle size distribution is also important for some applications.

Grades of Aluminium Alloy Powder

Aluminium alloy powder is manufactured into different established grades based on the alloy type:

  • 1xxx series powders – AA1100, AA1350
  • 2xxx series powders – AA2014, AA2024, AA2219, AA2519
  • 5xxx series powders – AA5083, AA5654
  • 6xxx series powders – AA6061, AA6082
  • 7xxx series powders – AA7050, AA7075

Higher number series indicate higher alloying levels and strength. Custom alloy compositions are also possible for proprietary grades.

Aluminium Alloy Powder Comparison

ParameterCold Gas AtomizationWater Atomization
Particle shapeHighly sphericalMore irregular, satellites
Particle size range15 – 180 microns5 – 350 microns
Size distributionTighter controlWider distribution
Apparent densityHigherLower
Production rateLowerHigher
CostHigherLower

Water atomized powders tend to have a cost advantage but suffer from less sphericity and broader particle distributions compared to gas atomized aluminium alloy powder.

Aluminium Alloy Powder Standards

Key standards for aluminium alloy powder:

StandardOrganizationDescription
AMS4200SAEAerospace material specification
ASTM B602ASTMChemical compositions and sieve sizes
EN1706CENEuropean standard specification
ISO13318ISOInternational standard for gas atomized and water atomized forms

Various national and organizational standards help ensure quality and consistency of aluminium alloy powder supply.

Global Suppliers of Aluminium Alloy Powder

SupplierLocationCapabilities
Valimet Inc.USAWide range of atomization, large capacity
Sandvik OspreyUKLeading supplier of controlled powders
TLS Technik GmbHGermanySpecialist in gas and water atomized powders
Fukuda Metal Foil & Powder Co.JapanBroad alloy offerings
SCM Metal ProductsSingaporeFocus on aluminum and copper alloys

Pricing for Aluminium Alloy Powders

Price for aluminum alloy powder varies based on:

  • Alloy grade and characteristics
  • Particle shape and size specifications
  • Purchase quantity and lot size
  • Regional tariffs and transportation
TypePrice Range
1xxx series$5 – $15 per kg
2xxx series$10 – $30 per kg
5xxx series$15 – $35 per kg
6xxx series$20 – $40 per kg
7xxx series$30 – $60 per kg

Prices above are approximate ranges for reference purpose only. Contact suppliers for exact current pricing based on your specific needs.

Advantages and Limitations of Aluminium Alloy Powder

Advantages

  • Lightweight compared to steel and titanium alloys
  • Achieve strengths exceeding many wrought product forms
  • Composition and properties can be customized
  • Low raw material cost compared to titanium or nickel alloys
  • Good corrosion resistance in many environments
  • High thermal and electrical conductivity
  • Variety of production processes possible from powder

Limitations

  • Lower strength than high alloy steels at elevated temperatures
  • Reactivity limits some processing approaches and applications
  • Producing high integrity large cross sections remains challenging
  • Cost is higher than conventional carbon steel powders
  • Some fatigue sensitive applications may require wrought products
  • Anisotropic properties and porosity issues in AM components
aluminium alloy powder

Frequently Asked Questions

What are the most common alloys used as aluminium alloy powder?

The most common alloy powders are: 2xxx series such as 2014 and 2024, 5xxx alloys like 5083, 6xxx alloys including 6061 and 6082, and 7xxx alloys with 7050 and 7075 being popular.

What particle size is best for metal injection molding using aluminium powders?

A particle size range between 15-45 microns is typically recommended for metal injection molding using aluminium alloy powders.

What types of atomization processes can produce aluminium alloy powder?

Gas atomization and water atomization are the two main industrial processes used. Rotating disk atomization method can also produce aluminum powders.

What is the benefit of using 5xxx series aluminum alloys for thermal spraying?

5xxx series Al alloys like 5083 have excellent corrosion resistance while remaining dimensionally stable at elevated temperatures making them suitable for thermal spray coatings for marine and chemical exposures.

What affects the pricing of aluminum alloy powder?

The alloy composition, particle characteristics like size and shape, order volume, regional tariffs and transportation costs determine the final pricing from different aluminum powder suppliers.

What standards apply to aluminum alloy powders for additive manufacturing uses?

Key standards include ASTM B602, AMS4200, EN1706, and ISO 13318. Additional AM-specific standards are under development to address process-related requirements.

Can aluminum alloy powder be reused?

Reusing aluminum powder is generally not recommended for critical applications. Storage conditions can allow moisture pickup and oxidation limiting powder performance. Minor reuse may be possible in non-critical applications with appropriate testing.

Are higher number aluminum alloys always stronger than lower number alloys?

In general, higher number 2xxx, 6xxx, and 7xxx series powders have higher strength than 1xxx or 5xxx alloys, but significant overlap can exist based on exact composition, powder characteristics and processing history. Always check supplier data for guaranteed powder properties.

Why is porosity and anisotropy a concern for AM made aluminum components?

High thermal conductivity and reflectivity of aluminum combined with rapid solidification during laser or e-beam melting hinders optimal fusion and gas bubble escape leading to defects. Different mechanical properties parallel and transverse to build layers also arise.

Can I mix different aluminum alloy powders to create custom grades?

It is generally not advisable to mix powders to create intermediate or custom alloys due to risks of incomplete mixing, alloy reactions, or inadequate particle bonding during part manufacture. Consult closely with your powder supplier when exploration property combinations.

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