News - Expansion alloy materials

Expansion alloy is a kind of alloy with special thermal expansion properties. In a certain temperature range, Dilatant alloy materials coefficient of thermal expansion (CTE) either remains extremely low (low expansion alloys), or can match the coefficient of thermal expansion of other materials (such as glass, ceramics, etc.) (constant expansion alloys). Thermal expansion alloys can effectively control their own dimensional changes when the temperature changes, thus meeting a variety of high precision and other applications.

Expansion alloys are divided into low expansion alloys, constant expansion alloys and high expansion alloys:

The typical representative of low – expansion alloys is Invar alloy (4J36), also known as Invar36, Nicloy36, SimondslnVar136. Designation of precision alloys. The characteristic of Invar alloy is that it has a very low coefficient of thermal expansion within a wide temperature range. This is because the alloy contains elements such as nickel, and these elements play a role in suppressing thermal expansion in the crystal structure of the alloy. When the temperature changes, the change in the inter – atomic forces of the alloy is relatively small, so that the overall dimensional change is minimal.

Characteristics: The low – expansion Fe – Ni alloy (Invar alloy) has a low linear coefficient of thermal expansion in the range of 20°C – 100°C.

Uses: It is used to manufacture various instrument and meter parts that require dimensional stability, or the passive layer of thermostatic bimetal, and resonant cavities. Besides 4J36, there are some other similar low – expansion alloys, which play an important role in low – temperature physics experimental devices, high – precision optical instruments and other fields.

Invar36 alloy Chemical Element Content (%):

Composition

Min

Balance

0.2

Max

0.6

0.05

0.3

0.02

The controlled – expansion alloys such as Kovar alloy (4J29), also know as Kovar, FeNi28Co18. kovar alloy coefficient of thermal expansion can be similar to that of materials such as glass and ceramics within a certain temperature range. This is achieved by adjusting the chemical composition of the alloy (mainly including elements such as iron, nickel, and cobalt). In the electronics industry, Kovar alloy is used to make the sealing components of electronic tubes, transistors and other electronic components with glass or ceramics. Characteristics: The controlled – expansion iron – nickel – cobalt alloy for glass – to – metal seals, Kovar alloy, has an expansion coefficient similar to that of hard glass within a certain temperature range.The controlled expansion alloys is used for matched sealing with hard glass in the vacuum industry. There are also other materials of controlled – expansion alloys such as 4J42 and 4J50 (FeNi 50) etc.

Kovar Chemical Element content (%):

Composition

Min

Balance

28.5

16.8

Max

29.5

17.8

0.03

0.3

0.5

0.02

0.2

High expansion alloy:

High expansion alloys are special materials whose thermal expansion coefficient is significantly higher than that of common metals. This type of alloy is usually composed of multiple metal elements, through a specific ratio to achieve high expansion characteristics.

Expansion alloys have thermal expansion properties, good processing properties, and stable physical and chemical stability, and are widely used in the electronics industry, precision instrumentation, aerospace and other industries.

Post time: Jan-16-2025