Nickel Alloy Powders for 3D Printing

Nickel alloys offer excellent corrosion resistance, heat resistance, and mechanical properties. This makes them suitable for additive manufacturing of complex components exposed to extreme environments. This article provides an overview of key nickel alloy powder grades, properties, applications, specifications, and suppliers.

Overview of nickel alloys powder

Nickel alloy powders can be used to print intricate metal parts with properties unmatched by other materials using powder bed fusion or directed energy deposition processes.

Alloy systems: Ni-based superalloys, stainless steels, alloy steels, nickel copper alloys, nickel cobalt alloys, and nickel titanium shape memory alloys.

Powder production: Mainly gas atomized with some plasma atomization; spherical morphology and controlled size distribution.

Powder sizes: From 15 microns to 150 microns depending on alloy; finer sizes for better resolution.

Key properties: Heat resistance, corrosion resistance, wear resistance, strength at high temperatures.

Composition and Microstructure

Nickel alloy chemistry, phases present, defects formed during printing, and microstructural features determine properties.

Common nickel alloys

Alloy	Nickel	Chromium	Iron	Niobium	Molybdenum	Aluminum + Titanium	Carbon
Inconel 718	50-55%	17-21%	Bal.	4.75-5.5%	2.8-3.3%	0.65-1.15%	0.04% max
Inconel 625	58% min	20-23%	2% max	3.15-4.15%	8-10%	0.4% max	0.1% max
Hastelloy X	Bal.	21-25%	18% max	–	8-10%	0.3-1.0%	0.15% max

Microstructure: Mix of gamma nickel FCC matrix and carbide, boride, or intermetallic precipitates. Cooling rate affects grain size and precipitates.

Porosity and cracks: Process-induced lack of fusion defects degrade properties and fatigue resistance. Hot isostatic pressing (HIP) helps reduce porosity in nickel alloys.

Properties and Performance

Nickel alloy parts properties depend on composition, AM process variables, build orientation, heat treatment, HIP and testing direction.

Physical properties

Alloy	Density (g/cc)	Melting point (°C)	Thermal conductivity (W/m-K)	Coeff. of thermal expansion (10-6/K)
Inconel 718	8.19	1260-1336	11.4	13.0
Inconel 625	8.44	1260-1350	9.8	13.1
Haynes 282	8.24	1310-1375	11.1	13.3

Mechanical properties

Alloy	Yield strength (MPa)	Tensile strength (MPa)	Elongation (%)	Hardness (HRC)
As-printed Inconel 718	500-900	900-1200	10-25	30-45
HIP Inconel 718	690-830	1035-1240	12-22	36-43
As-printed Hastelloy X	450-650	760-900	30-35	25-35
Haynes 282	485-550	860-1030	25-40	30-36

High temperature properties: Excellent creep rupture, stress rupture, oxidation and hot corrosion resistance up to 700°C for nickel superalloys.

Applications of Nickel Alloy Additive Manufacturing

Unique geometries and properties expand uses for 3D printed nickel alloy components.

Aerospace: Turbine blades, combustors, thrust chambers

Oil and gas: Wellhead valves, subsea manifolds, separators

Nuclear: Reactor vessels and internals exposed to high temperatures, pressure and irradiation

Automotive: Turbocharger wheels and housings, supercharger rotors, fuel injector nozzles

Chemical: Pumps, valves, heat exchanger tubes, reaction vessels corrosion resistance

Tooling: Conformal cooling channels integrated into injection molds for plastics

Food and pharmaceutical: Hoppers, conveyors compatible with CIP/SIP and industry hygiene standards

Popular Nickel Alloy Powder Grades

Alloy	Printability	Corrosion Resistance	Heat Resistance	Cost
Inconel 718	Excellent	Moderate	Excellent	High
Inconel 625	Very good	Excellent	Very good	Very high
Hastelloy X	Moderate	Excellent	Excellent	High
Haynes 282	Good	Moderate	Excellent	Moderate
17-4PH Stainless	Excellent	Moderate	Moderate	Low

Specifications

Stringent quality standards enforced for aerospace, nuclear and food contact compliance.

Powder specifications

Parameter	Requirement	Test method
Particle size distribution	15-100 μm for EBM; 5-45 μm for SLM	Laser diffraction
Apparent density	≥ 3 g/cc	Hall flowmeter
Tap density	≥ 4 g/cc	Tap density tester
Flow rate	15-25 s/50g	Hall flowmeter
Composition	Certified COA	GDMS, ICP-OES

Part qualification standards

Industry	Standard
Aerospace	AMS7000, ASTM F3056
Nuclear	ASME Section III Subsection NG
Food	ASME BPE-2022
Medical	ISO 13485, ASTM F3122

Design Rules in Nickel Alloys AM

Optimize designs to fully exploit benefits of AM with nickel alloys.

• Reduce weight with lattices and thin walls
• Conformal cooling channels in tools
• Allow for HIP capsule access
• Minimize trapped powder
• Optimize support structures
• Accommodate stresses from rapid solidification
• Account for thermal distortion and warpage

Suppliers

Leading providers of nickel alloy powders for additive manufacturing.

Supplier	Materials Offered	Size Range (μm)
Carpenter Additive	IN625, IN718, Custom Age 625Plus®, 17-4PH, more	10-105
Sandvik	Osprey® IN, NO, NB alloys	5-150
Praxair	IN718, IN625, HX, Custom Alloys	15-45
AP&C	IN625, IN718, IN713, Custom Alloys	15-53
LPW Technology	IN718, CM247LC, Haynes 282®	15-45

Cost: ~$100-$300 per kg for nickel alloy powders depending on order quantity, composition, size distribution and other requirements.

FAQs

Q: Why choose laser powder bed fusion over directed energy deposition for nickel alloys?

A: L-PBF methods like SLM and EBM offer better resolution, higher density, finer surface finish, and more precise metallurgy than DED which has higher build rates but poorer quality.

Q: Which heat treatment is used for additively manufactured nickel superalloys?

A: For Inconel 718, a standard aging treatment involves heating to 720°C, holding for 8 hours, then air cooling to precipitation harden the alloy with gamma prime and gamma double prime phases.

Q: Can all nickel alloys be easily 3D printed?

A: Alloys like nickel-titanium shape memory alloys present challenges due to their susceptibility to oxidation and complex solid-state phase transformations during printing. Special atmospheres or parameter modification is needed.

Q: How to minimize cracking in AM nickel alloy parts?

A: Carefully controlling the thermal gradient direction and peak temperatures reduces hot tearing. Using preheated platforms also lowers thermal stresses. Optimizing scan strategy helps if microcracks form from stresses between deposited layers.

Q: Which post-processing method gives the best surface finish on nickel alloy AM components?

A: Automated drag finishing gives Ra values under 0.4 microns while manual hand polishing allows intricate features or internal channels to be smoothed depending on accessibility needs. Anodizing can also improve surface finish. Match post-process method to application.

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