Alloy 48

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A nickel-iron controlled-expansion alloy containing 48% nickel. Its coefficient of thermal expansion is designed to match that of soft lead and soda-lime glasses. The alloy also has a high inflection point. Used for glass-to-metal seals in radio valves and incandescent electric light bulbs and for industrial thermostats that operate at temperatures up to 840°F (450°C).

Alloy 48 Chemistry maximum % unless noted

Fe Ni Co C Si S Cr
Bal 48 -- 0.05 0.30 0.02 0.025

Physical Properties

Brand Density Melting point
Alloy 48 8.20 g/cm³ 1450°C


Super alloy 48 is suitable for usage in industrial thermostats operating at temperatures up to 450°C (840°F). This alloy is also used for glass-to-metal seals in incandescent electric light bulbs and radio valves.