Fusible Alloys

Helper alloys that offer low-melting temperatures for a range of applications, typically to supply mechanical support for work pieces during finishing.

Features & Benefits

The key property of fusible alloys is their low-melting points which allows for ease of use in applications such as supporting work pieces during finishing stages. Because of the low-melting point, it is easy to re-melt and remove this sacrificial material after the finishing process.

In some applications, it is the precise location where the melting point of the alloy can be utilized. For example, the melting property of the material can serve as a precise switch when it reaches the desired temperature, such as in sprinkler systems. The same principle has been used in pop-up timers when cooking turkeys.

Alloys with even lower melting points contain gallium and can be found on our Liquid Alloys Page.

To find an alloy to meet your needs, you can use our Solder Alloy Guide.

Fusible Alloys

Indium Corporation Fusible Alloys

Our materials, classified by Indalloy® number, offer a wide range for desired liquidus/solidus/melting point locations on the temperature scale. The chart below shows an excerpt. Indalloy®15 (Solidus: 38°C; Liquidus 43°C) is at the low end of the spectrum. Twenty-eight Indalloy compositions can be found up to 100°C, including 10 eutectic alloys, and four compositions that are Pb- and Cd-free.

Low Temp Alloys - Melting Properties - Ranked by Liquidus
Low Temp Alloys - Melting Properties - Ranked by Solidus

The complete data set can be accessed in our solder alloy directory.

Low-temperature alloys contract or expand after solidifying and, depending on their crystal structure, undergo crystal growth and re-crystallization during the cool-down period. Thus, initial growth can be followed by shrinkage (for example, Indalloy®117), or initial shrinkage can be followed by expansion (Indalloys 160–190). Utilizing an expanding alloy can be an advantage in cases where cavities (or crevices in a complex shape) need to be filled without any voiding.

In addition, some alloys have close to zero expansion/shrinkage (Indalloys 281–338). Despite the relatively large range between liquidus and solidus, these are used in applications where the alloy is cast into convex cavities. After extraction, the (positive) cast replicates exactly the (negative) shape of the cavity and its dimensions, allowing for easy and precise measurements that otherwise cannot easily be performed.

Applications for Fusible Alloys

The helper function of low-melting point alloys is most often utilized for lens grinding. In the lens blocking application, the fusible alloy is melted onto the curved surface of a glass lens which is then held (and simultaneously protected) while the other side of the lens can be finished to the curvature needed. After grinding, the fusible alloy can simply be removed by melting it with hot water.

Another mechanical helper application is found in the finishing of turbine blades. These work pieces have complex curved shapes that can’t easily be clamped down and need to be protected while finishing the attachment (firtree fixing) that controls the precise angle of the blade. Again, the fusible alloy provides protection and mechanical support while easily being removed after the operation.

  • Lens blocking
  • Turbine blade finishing
  • Helper alloys for mechanical support and protection during finishing operations
  • 3D printing
  • Dimensional analysis of cavities (e.g., gun chamber measurements)