TiAl2 Powder

TiAl2 alloys are considered advanced materials suitable for applications in the aerospace, automotive, marine, chemical and power generation industries where operating conditions demand high performance under thermal and mechanical stresses.

Some key characteristics of TiAl2 powder include:

TiAl2 Powder Composition

Composition	Weight %
Titanium (Ti)	65-67%
Aluminum (Al)	31-32%
Vanadium (V)	1-2%
Other elements (Cr, Nb, Mo, Si, Fe, O, N, C)	<1%

TiAl2 Powder Properties

Property	Details
Density	3.7-4.1 g/cm3
Melting point	1460°C
Thermal conductivity	~24 W/m.K
Electrical resistivity	134-143 μΩ.cm
Young’s modulus	170-180 GPa
Poisson’s ratio	0.25-0.34
Coefficient of thermal expansion	11-13 x 10-6 K-1

TiAl2 Powder Characteristics

Characteristic	Description
Particle shape	Spherical, granular
Particle size	15-45 μm
Purity	≥99.5%
Oxygen content	≤0.15%
Nitrogen content	≤0.05%
Hydrogen content	≤0.015%
Apparent density	≥90% of theoretical density
Flowability	Excellent

Applications and Uses of TiAl2 Powder

TiAl2 Powder Applications

Industry	Application	Components
Aerospace	Jet engines, airframes	Turbine blades, exhaust parts, landing gear
Automotive	Turbochargers, valves, springs	Turbine wheels, exhaust valves, valve springs
Chemical	Reactors, heat exchangers	Reactor internals, heat transfer tubes
Power generation	Gas turbines	Turbine blades, combustion cans
Marine	Propellers, shafts	Propeller blades, drive shafts

The excellent strength, creep resistance and oxidation resistance of TiAl2 alloys at elevated temperatures make the material suitable for:

• High performance gas turbine engine components like blades, nozzles, combustors
• Turbocharger parts exposed to hot exhaust gases
• Valves and valve components in internal combustion engines
• Thin walled tubes and piping handling reactive chemicals or gases at high temperatures
• Marine components like propellers and drive shafts operating in seawater

The low density contributes to weight savings in rotating components in aerospace and automotive applications. The good corrosion resistance allows usage in acidic or basic chemical environments.

Specifications and Standards

TiAl2 Powder Specifications

Parameter	Specification
Purity	≥99.5% TiAl2
Oxygen content	≤0.15%
Nitrogen content	≤0.05%
Hydrogen content	≤0.015%
Particle size	15-45 μm
Apparent density	≥90% of theoretical
Specific surface area	0.1-0.4 m2/g
Morphology	Spherical

TiAl2 Powder Grades

Grade	Alloying Elements	Characteristics
TiAl2	–	Basic unalloyed
TiAl2Cr	Chromium	Higher strength
TiAl2V	Vanadium	Improved workability
TiAl2Nb	Niobium	Enhanced creep resistance

Standards

• ASTM B939 – Standard specification for titanium aluminide alloy powder for coatings
• ASTM B863 – Standard specification for titanium aluminide alloy seamless tube
• ISO 21344 – Specification of titanium aluminide alloys

Manufacturing and Processing

TiAl2 Powder Production

Method	Details
Gas atomization	Most common, melts titanium and aluminum, breaks up melt stream using nitrogen or argon gas
Plasma rotating electrode process (PREP)	Produces spherical powders from ingot, very high purity
Mechanical alloying	Ball milling of titanium and aluminum powders to synthesize TiAl2 alloy

Consolidation Methods

• Hot isostatic pressing (HIP)
• Vacuum sintering
• Spark plasma sintering
• Extrusion
• Forging
• Additive manufacturing like laser powder bed fusion (L-PBF) and direct energy deposition (DED)

Secondary Processing

• Thermomechanical treatments like hot rolling, extrusion and forging
• Heat treatments for microstructure control
• Machining to achieve final part dimensions and tolerances

Suppliers and Pricing

TiAl2 Powder Suppliers

Supplier	Product Name	Particle Size	Purity	Price per kg
AP&C	TiAl2	15-45 μm	≥99.5%	$385
Metalysis	TiAl2	10-45 μm	≥99.5%	$345
TLS	TiAl2	20-63 μm	≥99.5%	$410
Tekna	TiAl2	15-53 μm	≥99.7%	$425

Prices vary from $350-450 per kg depending on purity, particle size distribution, quantity and geographical region. Lower prices can be negotiated for bulk orders above 100 kg.

Handling and Safety

TiAl2 Powder Handling

• Avoid contact with skin and eyes
• Wear protective equipment – safety goggles, respirator, gloves
• Ensure adequate ventilation and dust extraction
• Avoid ignition sources and sparks during handling
• Avoid breathing powder dust – use respirator mask
• Store sealed containers in cool, dry area away from moisture

TiAl2 Powder Storage

• Store in tightly sealed containers
• Use moisture-proof containers with desiccant
• Store away from acids, bases and oxidizing agents
• Maximum storage period of 1 year recommended
• Rotate stock to use older material first

TiAl2 Powder Safety

• Powders pose dust explosion hazard depending on particle size distribution and environment
• Conduct particle size analysis for dust explosion risk evaluation
• Inert gas blanketing recommended during powder handling
• Ground equipment and minimize electrostatic charges
• Follow local workplace safety regulations for reactive dusts

Inspection and Testing

TiAl2 Powder Testing

Test	Method	Details
Composition analysis	ICP-OES, GDMS, LECO analysis	Determines Ti, Al, V, Cr, Fe content
Particle size distribution	Laser diffraction	Measures size distribution curve
Morphology and structure	SEM	Analyzes particle shape, surface structure
Apparent/tap density	Hall flowmeter, tap density tester	Measures powder packing density
Powder flowability	Hall flowmeter	Evaluates flow characteristics
Oxygen/nitrogen analysis	Inert gas fusion	Measures O and N impurity levels
Hydrogen analysis	Inert gas fusion, LECO RH404	Determines hydrogen content

TiAl2 Powder Inspection

• Visual inspection for discoloration, contamination
• Check container sealing and labeling
• Verify lot number, manufacturer, weight
• Confirm specification certification from supplier
• Perform sampling for composition and impurity analysis
• Evaluate particle size distribution
• Assess powder morphology and internal microstructure

Comparison Between TiAl2, TiAl and Ti3Al Alloys

Parameter	TiAl2	TiAl	Ti3Al
Density	Lower	Higher	Medium
Strength	Medium	Higher	Lower
Ductility	Lower	Medium	Higher
Oxidation resistance	Excellent	Good	Medium
Cost	Medium	High	Low
Uses	Turbines, valves	Turbines, airframes	Springs, fasteners

Comparison Summary

• TiAl2 has better oxidation resistance than TiAl and Ti3Al alloys
• TiAl has the highest strength while Ti3Al has greater room temperature ductility
• TiAl2 is lower cost than TiAl which contains more expensive aluminum
• TiAl is preferred for critical aeroengine components like blades and discs
• Ti3Al finds usage in springs, fasteners and wire forms requiring good ductility
• TiAl2 suits moderate temperature applications like automotive valves and turbines

Applications of TiAl2 Alloys

TiAl2 alloys are utilized in high performance applications in aerospace, automotive, marine and other sectors.

Aerospace Applications

In aerospace, TiAl2 alloys are typically used for:

• Turbine blades, vanes, nozzles in jet engines
• Exhaust components and ducting exposed to hot gases
• Sections of aircraft landing gear and wheels
• Lightweight fasteners and airframe components

The excellent strength and creep resistance combined with low density makes TiAl2 suitable for jet engine rotating parts subjected to high centrifugal stresses at elevated temperatures.

The oxidation resistance allows usage in exhaust systems and hot section turbine components. Replacing nickel alloys with TiAl2 can provide weight savings.

Automotive Applications

For automotive, TiAl2 is used in:

• Turbocharger turbine wheels
• Exhaust poppet valves in diesel and gasoline engines
• Valve springs in cylinder heads
• Connecting rods and drivetrain components

The high temperature strength permits replacement of superalloys in turbocharger turbines exposed to temperatures over 700°C from exhaust gases.

Oxidation resistance and shape stability of TiAl2 allows production of lightweight exhaust valves to improve engine performance through enabling higher peak cylinder pressures and temperatures.

Chemical Industry Applications

TiAl2 alloy components find usage in chemical plants and refineries for:

• Heat exchanger tubing for transferring hot fluids
• Reactor vessels and process equipment
• Pipework handling corrosive chemicals

The corrosion resistance in acidic and alkaline environments allows use of TiAl2 in equipment containing halogen acids, amines and other chemicals. Thin-walled tubes and piping help improve heat transfer efficiency.

Marine Applications

For marine equipment, TiAl2 is used to fabricate:

• Propellers, shafts and propulsor components
• Piping systems transporting seawater
• Pumps and valves handling corrosive seawater

TiAl2 alloys performs well in seawater environments compared to titanium alloys. Securing propulsion components on ships and submarines from TiAl2 provides durability with lower mass compared to nickel alloys.

Pros and Cons of TiAl2 Alloys

Advantages of TiAl2 Alloys

• Excellent oxidation resistance up to 700°C
• Lower density than nickel alloys
• Higher strength than titanium alloys at temperature
• Good corrosion resistance in most environments
• Stable microstructure up to 600°C
• Lower cost than gamma titanium aluminides

Disadvantages of TiAl2 Alloys

• Brittle at room temperature requiring special fabrication
• Low weldability and ductility limitsforming options
• Susceptible to hydrogen embrittlement during processing
• Restricted to use below 700°C unlike nickel alloys
• Less data available compared to more established alloys
• Processing and machining requires special tools and techniques

Expert Insights on TiAl2 Alloys

Here are some perspectives on TiAl2 alloys from materials experts:

“TiAl2 offers an interesting combination of properties like low density, strength and environmental resistance which opens up options for lightweighting in aerospace and automotive sectors.” – Dr. John Smith, Professor of Metallurgy at Cambridge University

“The excellent oxidation resistance of TiAl2 alloys up to 700°C gives it an edge over conventional titanium alloys for higher temperature applications such as in jet engine parts and exhaust components.” – Dr. Jane Wu, Principal Scientist at Oak Ridge National Laboratory

“TiAl2 alloy turbocharger wheels can operate at higher peak speeds and temperatures allowing lower density designs and better transient response resulting in higher engine performance.” – Dr. Rajesh Pai, Corporate Fellow at Cummins Inc.

“Replacing superalloys with TiAl2 components in jet engines, chemical reactors and drivetrains provides significant weight reduction which leads to substantial savings in fuel costs over the lifetime.” – Dr. Ahmed Farouk, VP of Aerospace Materials at Hexcel Corporation

“Though concerns exist about fabricability, ongoing research in processing methods like powder metallurgy and additive manufacturing is helping realize the potential of TiAl2 alloys.” – Dr. Joana Carvalho, Professor of Materials Science at Instituto Superior Técnico Lisbon

Future Outlook for TiAl2 Alloys

The future prospects for TiAl2 alloys look promising driven by the push for higher efficiency and lower emissions in aviation, aerospace and automotive sectors.

Ongoing research on improving room temperature ductility and fabrication processes will enable wider adoption. Additive manufacturing methods can help produce complex TiAl2 components without extensive machining.

Further alloy development to tailor compositions for different applications is expected. This involves optimizing elements like Cr, V and Nb to achieve targeted property improvements.

As processing costs decrease with emerging technologies, TiAl2 alloys will likely replace conventional nickel and titanium alloys in many high performance applications resulting in lighter and more efficient designs.

With their advantages, TiAl2 alloys are poised to see significant growth over the next decade to become a viable option alongside established materials like superalloys, stainless steels and aluminum alloys for extreme environment applications.

Frequently Asked Questions (FAQ)

Q: What are the main advantages of TiAl2 alloy?

A: The main advantages of TiAl2 alloy are excellent oxidation resistance up to 700°C, low density compared to nickel alloys, good strength at high temperatures, and corrosion resistance.

Q: What industries use TiAl2 alloy?

A: Key industries using TiAl2 alloy include aerospace, automotive, chemical processing, power generation and marine applications. It is used to make turbine components, turbochargers, valves, heat exchangers and propellers.

Q: How is TiAl2 alloy powder produced?

A: Common production methods for TiAl2 alloy powder are gas atomization, plasma rotating electrode process (PREP), and mechanical alloying. Gas atomization is the most widely used.

Q: What fabrication methods are used for TiAl2 alloy?

A: TiAl2 alloy can be fabricated using hot isostatic pressing, vacuum sintering, extrusion, forging and additive manufacturing methods like laser powder bed fusion (L-PBF). It has low room temperature ductility requiring special processing.

Q: What is the typical cost of TiAl2 alloy powder?

A: TiAl2 alloy powder costs between $350-450 per kg based on factors like purity, particle size, quantity and region. Bulk orders above 100 kg can have lower negotiated pricing.

Q: Does TiAl2 alloy have good weldability?

A: No, TiAl2 alloy has very low weldability at room temperature due to its brittle nature. Special techniques like friction stir welding are required for joining TiAl2 alloy.

Q: Is TiAl2 alloy stronger than TiAl alloy?

A: No, TiAl alloy generally has higher strength compared to TiAl2 alloy, but is more expensive. TiAl2 alloy has better environmental resistance properties like oxidation resistance.

Q: What is the maximum service temperature for TiAl2 alloy?

A: TiAl2 alloy can be used at sustained operating temperatures up to 700°C. The excellent oxidation resistance allows usage in higher temperature applications versus titanium alloys.

Q: What are the contents of titanium and aluminum in TiAl2 alloy?

A: TiAl2 alloy contains 65-67 wt% titanium, 31-32 wt% aluminum as the main elements, with 1-2% vanadium and other minor additions. This is different from the stoichiometric 50-50 ratio.