Alloy 48 is a controlled expansion alloy with nickel content is 48%.
Next Generation Metals has this available as rod, bar, strip and coil.
Also known as Pernifer 48, NILO 48, Glass Seal 48.
Specifications:
UNS K94800, ASTM F-30, MIL 1-23011 Class 3
Applications:
Metal seals for electronic tubes, automotive and industrial lamps, specialty hermetic devices.