CoCrFeNi Powder

Overview of CoCrFeNi Powder

CoCrFeNi powder, also known as CoCrFeNiMn powder or high entropy alloy (HEA) powder, refers to a material composed of cobalt, chromium, iron, and nickel elements in near-equiatomic ratios. This novel alloy powder displays exceptional properties compared to conventional alloys and has garnered significant interest for various applications.

Some key features of CoCrFeNi powder include:

• High configurational entropy leading to outstanding strength, hardness, thermal stability, and corrosion resistance
• Single solid-solution FCC phase microstructure
• Excellent strength-ductility combination
• High fracture toughness
• Good machinability and formability
• Resistance to softening at elevated temperatures
• Customizable with minor additions of elements like manganese

The unique disorder in the atomic arrangement of CoCrFeNi imparts superior mechanical performance. The near-equal concentrations of the main elements hinder dislocation movement, improving hardness. The multiphase structure provides solid solution strengthening through lattice strain effects.

Composition of CoCrFeNi Powder

The composition of CoCrFeNi HEA powder can be tailored but generally consists of:

Element	Typical Composition Range
Cobalt (Co)	20-35 at.%
Chromium (Cr)	20-35 at.%
Iron (Fe)	20-35 at.%
Nickel (Ni)	20-35 at.%

The equiatomic ratio provides maximum configurational entropy but minor deviations do not significantly affect properties. Additions of 1-2 at.% of manganese are common to further improve properties through grain refinement and precipitation strengthening.

Properties of CoCrFeNi Powder

CoCrFeNi alloy powder exhibits a unique combination of outstanding properties:

Property	Values
Density	7.5-8.3 g/cm3
Melting Point	>1200°C
Microhardness	2.5-4 GPa
Ultimate Tensile Strength	500-1300 MPa
Yield Strength	200-1100 MPa
Elongation	10-60%
Young’s Modulus	150-250 GPa
Shear Modulus	65-85 GPa
Poisson’s Ratio	0.21-0.33
Fracture Toughness	>100 MPa√m
Thermal Conductivity	10-30 W/mK
Electrical Resistivity	70-100 nΩm
Corrosion Resistance	Excellent in various environments

The high hardness arises from solid solution strengthening while the FCC structure imparts good ductility. The properties can be tailored through composition adjustments and processing.

Characteristics of CoCrFeNi Powder

Some salient characteristics of CoCrFeNi alloy powder include:

• Single phase FCC structure lacking intermetallic phases
• Annealing twins and stacking faults present
• Equiaxed powder morphology with good flowability
• Powder size distribution ranging from 15-150 μm
• High purity with low oxygen content
• Spherical powder shape and smooth surface
• Customizable powder size, shape, and composition

The powder exhibits high chemical homogeneity with a uniform distribution of alloying elements. The spherical morphology provides good packing and flow characteristics.

Applications of CoCrFeNi Powder

The exceptional combination of strength, toughness, and processability of CoCrFeNi powder makes it suitable for:

Additive Manufacturing: Excellent printability due to good flow and melting characteristics. Used for aerospace, tooling, and biomedical implants.

Thermal Spray Coatings: Resistance to wear, corrosion, and thermal softening. Coatings for mechanical, marine, and chemical applications.

Alloy Development: Base material for new high entropy alloys with additions of Al, Ti, etc.

Metal Injection Molding: High stiffness parts with good dimensional stability for aviation and automotive.

Powder Metallurgy: High performance P/M parts with balanced strength and ductility.

Cryogenic Applications: Retention of ductility and toughness at subzero temperatures.

Specifications of CoCrFeNi Powder

CoCrFeNi alloy powder is available in various size ranges, compositions, and forms:

Parameter	Variants
Size range	15-25 μm, 25-45 μm, 45-75 μm, 75-105 μm, 105-150 μm
Composition	Equiatomic, custom elemental ratios
Powder shape	Spherical, irregular
Production method	Gas/water atomization, mechanical alloying
Supply form	Loose powder, sintered preforms

Larger powder sizes of 45-150 μm are preferred for thermal spray and metal injection molding. Finer 15-45 μm sizes are used for additive manufacturing. Powders can be customized in shape, size, oxygen content, and flowability.

Suppliers of CoCrFeNi Powder

Some leading global suppliers of CoCrFeNi high entropy alloy powder include:

Company	Production Capacity	Location
Sandvik	200 tons per year	Sweden
Praxair	150 tons per year	USA
Hoganas	100 tons per year	Sweden
CNPC Powder	50 tons per year	China
Carpenter Technologies	40 tons per year	USA

The powders are generally produced via gas or water atomization methods. Custom powder compositions and sizes can be sourced from these suppliers.

Pricing

Powder Size	Price Range
15-45 micron	$150-200 per kg
45-105 micron	$100-150 per kg
105-150+ micron	$80-120 per kg

Larger powder sizes are cheaper due to higher production rates in atomization. Custom alloys and compositions are priced higher. The powder prices have been declining due to increasing market competition and capacities.

Pros and Cons of CoCrFeNi Powder

Advantages	Limitations
Outstanding strength and hardness	High material costs due to Co and Ni
Excellent ductility and toughness	Limited data on long-term performance
Good fabricability by AM, MIM, PM	Processing challenges with microstructural control
Thermal and microstructural stability	Composition must be precisely controlled
High corrosion and wear resistance	Lower processability than conventional alloys
Retains strength at elevated temperatures	Often requires HIP post-processing

CoCrFeNi HEA powder enables components with unmatched property combinations. However, the material and processing costs are high. Microstructure and properties depend heavily on precise composition control.

Comparison with Alternatives

Vs. Stainless Steel Powders

• Higher strength and hardness
• Superior wear and corrosion resistance
• More expensive base material cost
• Lower processability and weldability

Vs. Tool Steel Powders

• Better ductility and fracture toughness
• Lower high-temperature strength
• Less established processing methods
• Limited size and alloy variant availability

Vs. Inconel Superalloy Powders

• Comparable high-temperature strength
• Lower cost material
• Shorter track record of performance
• Restricted microstructural stability at very high temperatures

FAQs

Q: What is high entropy alloy (HEA) powder?

A: HEA powder contains multiple principal elements in near-equiatomic ratios to produce exceptional properties of strength, ductility, and stability. CoCrFeNi powder is a leading HEA.

Q: What are the typical sizes of CoCrFeNi powder available?

A: Common size ranges are 15-45 μm for AM, 45-105 μm for thermal spraying, and 105-150 μm for MIM and other applications. Finer and coarser sizes can be customized.

Q: What affects the price of CoCrFeNi alloy powder?

A: Powder size, composition, purity, production method, and order quantity determine pricing. Larger sizes over 100 μm cost less. Minor additions or tighter composition ranges increase cost.

Q: How is CoCrFeNi HEA powder produced?

A: Gas atomization and water atomization are the main production methods. The powder can also be made by mechanical alloying or cryomilling of prealloyed ingots.

Q: What are some example applications of CoCrFeNi powder?

A: Leading uses are additive manufacturing of tooling and aerospace components, thermal spray coatings for wear/corrosion resistance, alloy development, metal injection molding of automotive parts, and powder metallurgy of high-performance components.

Q: What are the key properties of CoCrFeNi HEA powder?

A: It exhibits an exceptional combination of high strength, hardness, ductility, fracture toughness, thermal stability, and corrosion resistance compared to conventional alloys.

Q: What are the limitations of CoCrFeNi powder?

A: High base material cost, processing challenges in controlling microstructure, limited long-term performance data, reduced weldability compared to steels are some disadvantages.

Q: How does CoCrFeNi powder compare with tool steels and stainless steels?

A: It has vastly higher strength and hardness but lower processability than stainless steels. Compared to tool steels, it provides superior fracture toughness and ductility.

Q: Is CoCrFeNi suitable for cryogenic applications?

A: Yes, it retains good ductility and toughness at sub-zero temperatures while conventional alloys become brittle. This makes it useful for cryogenic equipment.

Q: Can the composition of CoCrFeNi powder be customized?

A: Yes, suppliers can provide custom elemental ratios beyond the equiatomic composition. Common adjustments are 1-2 at.% Mn or Co additions to tailor the properties.