Exotic Alloy

Exotic Alloys, also known as Super Alloys, are engineered to deliver exceptional performance in the most demanding environments. These advanced materials are composed of high concentrations of metals such as nickel, cobalt, copper, vanadium, tantalum, tungsten, zinc, and occasionally even silver and gold. Their superior mechanical and chemical properties enable them to withstand extreme conditions involving high temperature, pressure, and corrosive media.

Nickel and its alloys have long been indispensable across numerous industries due to their exceptional versatility and ability to form stable alloys with most metals. This adaptability makes nickel alloys a preferred choice in critical applications where strength, corrosion resistance, and temperature stability are non-negotiable.

One of the defining characteristics of these alloys is their resistance to high-pressure environments and elevated temperatures. This makes them ideal for aerospace turbine components, jet engine blades, nuclear reactors, and chemical plants. Their outstanding corrosion resistance is especially valuable in marine applications — such as Monel alloys used in deep-sea mining and seawater equipment — and in aggressive chemical processing systems.

Exotic Alloys are non-ferrous, high-performance materials known for their strength, toughness, and resistance to oxidation, deformation, and chemical attack. Pure nickel, for example, is a bright, silver-white metal that is hard, ductile, and malleable — serving as the base for many of these advanced alloys. These characteristics make exotic alloys essential in sectors such as automotive, marine, aerospace, oil and gas extraction, petrochemicals, thermal processing, and power generation.

Chemical Composition of Exotic Alloys

Grade C Mn Si P S Cr Mo Cu Ni Fe Others
Alloy A286 Min - - - - - 17 2.8 - 50 Balance Ti 0.65, Al 0.2, Cb 4.75
Max 0.08 0.35 0.35 0.015 0.015 21 3.3 0.3 55 - B 0.006, Co 1.0, Ta 0.05
Alloy X750 Min - - - - 0.01 14 - - Remainder 5 Ti 2.25, Al 0.4, Nb 0.7
Max 0.08 1.0 0.5 - - 17 - 0.5 - 9 -
Alloy 218 Min - 7 3.5 - - 16 - - 8 Balance N 0.08
Max 0.1 9 4.5 0.04 0.03 18 - - 9 - N 0.18
Alloy 254 Exact 0.010 - - - - 20 6.1 - 18 55.69 N 0.20
SS 904L Min - - - - - 19 4 1 23 - -
Max 0.02 2 1 0.045 0.035 23 5 2 28 - -
XM-19 Min 0.06 4 - - 0.03 20.5 1.5 - 11.5 Balance N 0.2, Nb 0.1, V 0.1
Max 0.06 6 1 - 0.03 23.5 3 - 13.5 - N 0.4, Nb 0.3, V 0.3

Physical Properties of Exotic Alloys

Grade Property Metric Imperial
Alloy A286 Density 7.92 g/cm³ 0.286–0.287 lb/in³
Specific Gravity 7.92–7.94 7.92–7.94
Melting Range 1370–1430°C 2500–2600°F
Alloy X750 Density 8.26 g/cm³ 0.298 lb/in³
Melting Point 1413°C 2575°F
Alloy 218 Density 7.7 g/cm³ 0.28 lb/in³
Alloy 254 Density 8 g/cm³ 0.289 lb/in³
SS 904L Density 7900 kg/m³ –
Elastic Modulus 190 GPa –
Thermal Expansion (0–100°C) 15 μm/m/°C –
Thermal Conductivity at 100°C 11.5 W/m·K –
Specific Heat (0–100°C) 500 J/kg·K –
Electrical Resistivity 952 nΩ·m –
XM-19 Density 7.89 g/cm³ 0.285 lb/in³

Mechanical Properties of Exotic Alloys

Grade Property Metric Imperial
Alloy A286 Yield Strength 275 MPa 40,000 psi
Ultimate Tensile Strength 620 MPa 90,000 psi
Elongation – 40%
Alloy X750 Tensile Strength 1325 MPa 192.2 ksi
Elongation at Break (in 51 mm) 23.6% 23.6%
Reduction of Area 42% 42%
Alloy 218 Tensile Strength 724 MPa 105 ksi
Yield Strength 379 MPa 55 ksi
Poisson's Ratio 0.298 0.298
Elongation 35% 35%
Reduction of Area 55% 55%
Alloy 254 Tensile Strength 680 MPa 98,600 psi
Yield Strength 300 MPa 43,500 psi
Modulus of Elasticity 195 GPa 28,300 ksi
Shear Modulus 75 GPa 10,900 ksi
Poisson’s Ratio 0.30 0.30
Elongation at Break 50% 50%
Hardness, Brinell 210 210
SS 904L Tensile Strength (min) 490 MPa –
Yield Strength 0.2% Proof (min) 220 MPa –
Elongation (min) 36% –
Hardness 70–90 HR C (typical) / 150 HB –
XM-19 Tensile Strength at Break ≥ 689 MPa ≥ 100,000 psi
Yield Strength ≥ 379 MPa ≥ 55,000 psi
Elongation at Break ≥ 35% ≥ 35%

Characteristics of Exotic Alloys

Characteristics of Exotic Alloys
Exceptional high-temperature strength and oxidation resistance Superior corrosion resistance in aggressive environments Excellent fatigue and creep resistance
Good mechanical strength across a wide temperature range High resistance to pitting, crevice corrosion, and stress corrosion cracking Non-magnetic in annealed condition (for specific grades like XM-19)
Maintains structural stability under thermal cycling and high pressure Good weldability and fabricability Suitable for aerospace, marine, chemical, and nuclear applications

Grades of Exotic Alloys


Alloy - A286

Corrosion Resistance Properties of Alloy - A286

Type A-286 alloy content is similar in chromium, nickel, and molybdenum to some of the austenitic stainless steels. Consequently, A-286 alloy possesses a level of aqueous corrosion resistance comparable to that of the austenitic stainless steels. In elevated temperature service, the level of corrosion resistance to atmospheres such as those encountered in jet engine applications is excellent to at least 1300°F (704°C). Oxidation resistance of A-286 is high for continuous service up to 1500°F (816°C) and intermittent service up to 1800°F (982°C).

Processing Alloy - A286
Cold Working Super alloy A-286 is capable of being readily cold worked and a solution anneal heat treatment is recommended when this alloy is work hardened due to severe cold forming. • This solution anneal heat treatment will thus enable softening of super alloy A-286.
Welding Welding methods used for stainless steels are also recommended for super alloy A-286. • The area to be welded should be clean. • Post welding heat treatment or preheating is not recommended for this alloy. • Better welding results can be obtained when this alloy is solution annealed.
Forging Heavy forging and light forging are suitable for super alloy A-286. • Heavy forging is carried out between 1010-1204°C (1850-2200°F) and light forging between 871-1010°C (1600-1850°F).
Forming Conventional forming methods are used to readily hot or cold form super alloy A-286.
Machinability Conventional machining techniques are used to readily machine super alloy A-286. • This machining process involves turning, drilling and milling. • In the turning operations, the usage of cemented carbide tools is recommended for high cutting rates.
Aging Super alloy A-286 is first solution heat treated at 982°C (1800°F) before the aging process. Aging takes place for 16 h at 718°C (1325°F) after which this alloy is cooled in air.
Hardening Super alloy A-286 is hardened by the cold working process and is also capable of being age hardened due to the presence of titanium in this alloy.
Heat Treatment Super alloy A-286 is solution annealed at 982°C (1800°F), oil quenched, held for 16 h at 718°C (1325°F) and finally cooled in air. This heat treatment improves the strength of super alloy A-286.
Applications Super alloy A-286 is used in gas turbine forgings, fasteners, superchargers, cryogenic equipment, missile components, corrosive deep well hardware and jet engines.

Alloy - X750

Alloy X-750 is a precipitation hardenable Nickel-Chromium alloy with high strength at temperatures up to 1300°F (704°C) and oxidation resistance up to 1800°F (982°C). It offers excellent resistance to relaxation and as a result it is widely used for springs operating at elevated temperatures, It has high ductility and excellent properties at cryogenic temperatures.

Processing Alloy - X750
Machinability Alloy X750 alloy can be machined using conventional machining methods, which are used for iron-based alloys. Machining operations are performed using machining coolants. High-speed operations such as grinding, turning, or milling, are performed using water-base coolants. Drilling, broaching, tapping, or boring are performed using heavy lubricants.
Forming Alloy X750 alloy can be formed using all conventional techniques.
Welding: Alloy X750 alloy is welded using shielded metal-arc welding, gas-tungsten arc welding, gas metal-arc welding, and submerged-arc welding methods.
Heat Treatment Alloy X750 alloy is heat treated by annealing at 885 to 1149°C (1625 to 2100°F).
Forging Alloy X750 alloy is forged at temperatures ranging from 1205 to 1038°C (2200 to 1900°F).
Hot Working Alloy X750 alloy is hot worked at temperatures ranging from 983 to 1038°C (1800 to 2200°F).
Cold Working Alloy X750 alloy can be cold worked using standard tooling. Soft die materials such as bronze and zinc alloys, are used for providing good finish and reducing galling problems.
Annealing Alloy X750 alloy is annealed at 983 to 1038°C (1800 to 2000°F) followed by cooling.
Applications Alloy X750 alloy is mainly used in structural members of hot sections of gas turbines such as ducts, thrust reversers, discs.

Alloy - 218

Corrosion Resistance Properties of Alloy - 218

General corrosion resistance of Alloy 218 is between AISI 304 and 316. It offers better chloride pitting resistance, stress corrosion cracking resistance and crevice corrosion resistance than AISI 316L in laboratory conditions.

Processing Alloy - 218
Machinability Positive feeds, slow speeds, and resulphurized lubricants are suitable for machining super alloy NITRONIC60.
Forming Super alloy NITRONIC60 can be formed using standard techniques.
Welding: Super alloy NITRONIC60 can be welded using common welding techniques such as gas metal arc welding, gas tungsten arc welding, and submerged arc
Forging Super alloy NITRONIC60 is forged by heating at 1094°C (2000°F) followed by soaking.
Annealing Super alloy NITRONIC60 is annealed by soaking at 1038 to 1122°C (1900 to 2050°F) followed by quenching in water or air.
Hardening Super alloy NITRONIC60 can be hardened only by cold working.
Applications Internal combustion valves and seats, Pump components, Bridge spacers, Pin and roller bearings, High wear applications

Alloy - 254

Corrosion Resistance Properties of Alloy - 254

The high chromium content and particularly the molybdenum content gives 254 SMO excellent resistance to pitting and crevice corrosion. Tests in natural seawater at 60°C (140°F) have shown that SMO254 can be exposed for prolonged periods, without suffering crevice corrosion.

Processing Alloy - 254
Machinability Stainless steel grade 254 SMO™ is quite tough to machine due to the extremely high work hardening rate and lack of sulfur content; however using sharp tools, overpowered machine tools, positive feeds, good amount of lubrication, and slow speeds tend to provide good machining results.
Welding: Welding of stainless steel grade 254 SMO™ requires filler material without which it results in poor strength properties. Filler metals such as AWS A5.14 ERNiCrMo-3, and alloy 625 are recommended. Electrodes used in the process, have to match with AWS A5.11 ENiCrMo-12.
Annealing Annealing of this material should be performed at 1149-1204°C (2100-2200°F), which should be followed by a water quench.
Hot Working Forging, upsetting and other operations relating to this material can be performed at 982 - 1149°C (1800 - 2100°F). It is recommended that temperatures do not exceed this range as it would result in scaling and reduction in the workability of the material. To re-attain maximum corrosion resistant properties, it is advisable to perform post-process annealing.
Cold Working Cold working can be carried out using all the traditional methods; however the process would be tough due to its high work hardening rate. The result will provide the material with increased strength and toughness.
Hardening Stainless steel grade 254 SMO™ does not respond to heat treatment. Hardening is possible only through cold reduction.

Alloy - SS 904L

Corrosion Resistance Properties of Alloy - SS 904L

Grade 904L stainless steels have excellent resistance to warm seawater and chloride attack. The high resistance of grade 904L against stress corrosion cracking is due to the presence of high amounts of nickel in its composition. Moreover, the addition of copper to these grades develops resistance to sulphuric acid and other reducing agents in both aggressive and mild conditions. The corrosion resistance of grade 904L is intermediate between super austenitic grades, with 6% molybdenum content, and standard 316L austenitic grades. Grade 904L is less resistant to nitric acid than grades 304L and 310L, which are free of molybdenum. This steel grade needs to be solution treated following cold working, to achieve maximum stress corrosion cracking resistance under critical environments.

Processing Alloy - SS 904L
Heat Treatment Grade 904L stainless steels can be solution heat-treated at 1090 to 1175°C, following by rapid cooling. Thermal treatment is suitable for hardening these grades.
Welding Welding of grade 904L stainless steels can be performed using all conventional methods. This grade does not require pre-heat and post-weld heat treatments. Grade 904L can be subjected to hot cracking in constrained weldment. Grade 904L electrodes and rods are used for welding grade 904L steels according to AS 1554.6.
Fabrication Grade 904L stainless steels are high purity steels with low sulphur content. They can be machined using any standard methods. These grades can be readily bent to a small radius under cold conditions. Although subsequent annealing is not required in most cases, it should be carried out when the fabrication is performed under severe stress corrosion cracking conditions.

Alloy - XM 19

Corrosion Resistance Properties of Alloy - XM 19

NITRONIC 50 provides outstanding corrosion For many applications the 1950 F (1066 C) annealed condition provides adequate corrosion resistance and a higher strength level. In very corrosive media or where material is to be used in the as-welded condition, the 2050 F (1121 C) annealed condition should be specified. HighStrength (HS) NITRONIC 50 bars are useful for applications such as shafting and bolting, but do not quite exhibit the corrosion resistance of the annealed conditions in all environments.

Processing Alloy - XM 19
Machinability Machining Nitronic50 alloy requires slow speeds, positive feeds and abundant resulfurized lubricant.
Forming Nitronic50 alloy can be formed using all common forming techniques.
Welding: Nitronic50 alloy can be welded using all welding techniques such as gas tungsten arc, gas metal arc and submerged arc welding. Pre-heating is not required for this alloy.
Forging Nitronic50 alloy is forged at 1093°C (2000°F) and then heated to 1177°C (2150°F).
Annealing Nitronic50 alloy is annealed at 1038 to 1121°C (1900 to 2050°F) and quenched in water or air.
Hardening The alloy can be hardened through cold working.
Applications Fasteners, Marine hardware, Boat shafting, Pumps and valves, Sucker Rods for oil rigs.