Kovar® (Alloy K): Precision Controlled Expansion Alloy for High-Integrity Seals

1.3981 (FeNi29Co17) is an iron-nickel-cobalt alloy whose chemical composition is controlled within narrow limits to ensure precise and uniform thermal expansion and mechanical characteristics. These properties make it an ideal alloy for use in high integrity glass-to-metal and ceramic-to-metal seals, particularly where the application requires resistance to thermal shock. It shows the following features and properties:

Uniform thermal expansion characteristics

Properties

General

Property	Temperature	Value
Density	23.0 °C	8.25 g/cm³

Mechanical

Property	Temperature	Value
Elastic modulus	23.0 °C	139 GPa
Elongation	23.0 °C	30 %
Hardness, Vickers	23.0 °C	160 [-]
Tensile strength	23.0 °C	540 MPa
Yield strength	23.0 °C	380 MPa

Thermal

Property	Temperature	Value
Coefficient of thermal expansion	30.0 °C	4.6E-6 1/K
	450.0 °C	5.5E-6 1/K

Melting point		1450 °C
Specific heat capacity	23.0 °C	500 J/(kg·K)
Thermal conductivity	23.0 °C	17 W/(m·K)

Chemical properties

Property	Value
Cobalt	17 %
Iron	53 %
Nickel	29 %

Technological properties

Property
Application areas	General: Power and microwave tubes, transistors and diodes, lids and closures in a variety of hybrid electronic circuit packages.

Nilo® 52: High-Performance Controlled Expansion Alloy for Telecom Electronics Cu-DHP 1.4016 (40-20-40) – Key Material Properties

Metal