Controlled Expansion

Alloy ASTM F-15 (Kovar)

Iron54% Nickel29% Cobalt17%

Consisting of 29% Nickel, 17% Cobalt, and the balance Iron, this alloy is produced to ensure good properties for machining and deep drawing. Its expansion characteristics match borosilicate (Pyrex) glasses and alumina ceramics, and it is one of the most popular of the controlled expansion alloys for hermetic sealing.

Also known as: Kovar¹, Pernifer 2918² , Dilvar P1³ , Rodar1, NILO K⁴

Applications

• Power Tubes
• Microwave tubes
• Transistors
• Diodes
• Hybrid packages

Invar 36

Iron64% Nickel36%

Consisting of 36% Nickel, and the balance Iron, this alloy has very low expansion characteristics around ambient temperatures, and is often used where minimum expansion is required.

Also known as: Invar 36¹, Pernifer 36², NILO 36⁴, Invar³

Applications

• Optoelectronics
• Optical and laser benches
• Electronics
• Diodes
• Scientific instruments

Ultra 36

Fe44% Ni36% Si3N420%

A high quality Fe36Ni Metal Matrix Composite (MMC) reinforced with 20 vol.% micron scale silicon nitride ceramic. It is manufactured using a powder metallurgy methodology and a mechanical alloying process to ensure a homogeneous reinforcement distribution. This provides a refined grain structure for enhancing mechanical properties. The material has 10% lower density, lower CTE, good thermal stability and a higher yield over conventional wrought Fe36Ni alloys.

Applications

• Construction of satellites
• Cryogenics
• Opto-mechanical applications
• Production of carbon fibre reinforced polymers

Super Invar 32-5¹

Iron63% Ni32% Co5%

Consisting of 32% Nickel, 5% Cobalt, and the balance Iron, this alloy exhibits minimum thermal expansion (one half of Invar 36) at room temperature. It is often used in structural components, supports and substrates requiring precision measurements

Applications

• Optical and laser systems
• Telescopes
• Laser bench tops
• Ring laser gyroscopes

Alloy 52

Iron49.1% Nominal Nickel50.5% Nominal CobaltCarbon0.05% Silicon0.3% Sulfur0.025% Chromium0.025%

Consisting of 
51% Nickel, and the balance Iron, this alloy is used in a wide variety of electronic applications, especially for glass seals.

Also known as: Pernifer 50², NILO 50, Glass Seal 52¹

Applications

• Glass to metal seals for electronic tubes
• Automotive and industrial lamps
• Specialty hermetic devices

Alloy 48

Iron52% Nominal Nickel48%

Consisting of 48% Nickel, and the balance Iron this alloy is used in a variety of electronic applications, especially for glass and ceramic seals.

Also known as: Pernifer 48², NILO 48, Glass Seal 48¹

Applications

• Glass to metal seals for electronic tubes and hermetic devices

Alloy 46

Iron53.6% Nominal Nickel46% Carbon0.05% Silicon0.3% Sulfur0.025% Chromium0.025%

Consisting of 46% Nickel, and the balance Iron, this alloy is used in a variety of electronic applications, especially for glass and ceramic seals.

Also known as: Pernifer 46², NILO 46, Glass Seal 46¹

Applications

• Glass to metal seals for electronic tubes and hermetic devices

Alloy 42

Iron58.6% Nominal Nickel41% Carbon0.05% Silicon0.3% Sulfur0.025% Chromium0.025%

Consisting of 42% Nickel, and the balance Iron, this alloy is used in a wide range of electronic applications, lead frames, and especially for glass and ceramic seals.

Also known as: Pernifer 42², NILO 42⁴, Glass Seal 42¹

Applications

• Glass to metal seals for electronic tubes
• Hermetic packages
• Automotive and industrial lamps

Nickel 200 / 201 / 205 / 233

Nominal Nickel100%

Commercially pure, un-alloyed Nickel, used in electronics for packaging, leads, and lids.

Applications

• Getter tabs
• Heating element sheathing
• Anodes
• Special purpose electron tubes
• Fuel cells
• Ni-Cd batteries
• Transistor enclosures
• Spark gaps
• Terminals
• Anodes
• Cathodes
• Shields
• Semi-conductor supports

Nickel 270

Nominal Nickel100%

Commercially pure, powder metallurgy, un-alloyed Nickel, used in electronics for packaging, leads, and lids.

Applications

• Anodes plates
• Hydrogen thyratron components
• Cathode shanks
• Plater bars
• Transistor enclosures

Controlled Expansion Property Comparisons

Physical Properties	Kovar	Alloy 52	Alloy 48	Alloy 46	Alloy 42	Alloy 42-6	Invar 36	Super Invar 32-5
Density lb/cu in	0.302	0.3	0.298	0.295	0.293	0.293	0.291	0.294
Specific Gravity	8.36	8.3	8.25	8.17	8.12	8.12	8.05	8.15
Curie Temp °F	815	986	880	860	716	560	535	470
Curie Temp °C	435	530	471	460	380	293	279	245
Melting Point °F	2640	2600	2600	2600	2600	2600	2600	2600
Melting Point °C	1449	1427	1427	1427	1427	1427	1427	1427
Electrical Resistivity micro-ohm-cm	49	44	49	47	68	97	84	82
Electrical Resistivity ohm-cir mil/ft	294	258	290	277	400	570	495	481
Thermal Conductivity W/cm °C	0.17	0.14	0.13	0.11	0.11	0.13	0.10	0.10
Thermal Conductivity BTU- in/ sq. ft hr- °F	120	97	90	79.2	74.5	87	72.6	72.6
Specific Heat Cal/g- °C	0.11	0.12	0.12	0.12	0.12	0.12	0.123	0.12
Specific Heat BTU/lbm- °F	0.11	0.12	0.12	0.12	0.12	0.12	0.123	0.12
Thermal Expansion ppm/°F (75°F to 842°F)	2.9	5.5	5.0	4.4	3.9	5.9	4.9	4.5
Thermal Expansion ppm/°C (25°C to 450°C)	5.3	9.9	9.0	7.9	7.0	10.6	8.9	8.0

Mechanical Properties	Kovar	Alloy 52	Alloy 48	Alloy 46	Alloy 42	Alloy 42-6	Invar 36	Super Invar 32-5
Tensile Strength ksi	75	80	79	80	82	80	75	70
Tensile Strength MPa	518	552	545	552	566	552	518	483
Yield Strength ksi	40	40	36	35	34	40	40	40
Yield Strength MPa	276	276	248	242	235	276	276	276
Elongation % in 2 in.	30	35	30	30	30	30	34	40
Typical Hardness Ann. Rockwell	HRB 80	HRB 80	HRB 80	HRB 80	HRB 80	HRB 80	HRB 80	HRB 75
Modulus of Elasticity Mpsi	30	23	23	23	21.5	23	20.5	21.0
Modulus of Elasticity kMPa	207	159	159	159	148	159	141	145

Chemistry	Kovar	Alloy 52	Alloy 48	Alloy 46	Alloy 42	Alloy 42-6	Invar 36	Super Invar 32-5
maximum % unless noted
Iron	Bal	Bal	Bal	Bal	Bal	Bal	Bal	Bal
Nominal Nickel	29	50.5	48	46	41	42	36	32
Nominal Cobalt	17	–	–	–	–	–	0.5	5
Carbon	0.02	0.05	0.05	0.05	0.05	0.07	0.05	0.05
Silicon	0.20	0.30	0.30	0.30	0.30	0.30	0.40	0.25
Sulfur	–	0.025	0.025	0.025	0.025	0.025	0.015	0.015
Chromium	0.20	0.025	0.025	0.025	0.025	5.6 nom.	0.25	0.25
Titanium	–	–	–	–	–	–	–
Magnesium	–	–	–	–	–	–	–

Specifications	Kovar	Alloy 52	Alloy 48	Alloy 46	Alloy 42	Alloy 42-6	Invar 36
ASTM	F-15/ F-1466	F-30	F-30	F-30	F-30	F-31	F-1684
MIL	I-23011 CI 1	I-23011 CI 2	I-23011 CI 3	I-23011 CI 4	I-23011 CI 5	I-23011 CI 6	I-23011 CI 7
AMS	I-23011 CI 1	I-23011 CI 2	I-23011 CI 3	I-23011 CI 4	I-23011 CI 5	I-23011 CI 6	I-23011 CI 7