the.com/permalloy
the alloy so magnetically obedient it makes iron look stubborn and undisciplined.
means Permalloy is a nickel-iron alloy (roughly 80% nickel, 20% iron) prized for its extraordinarily high magnetic permeability, making it ideal for magnetic shielding and transformer cores.
from A blend of "permeability" — a material's willingness to be magnetized, from Latin "permeare," to pass through — and "alloy," from Old French "aloi," a mixing of metals (ultimately from Latin "alligare," to bind together). The name was coined in the early 20th century at Bell Telephone Laboratories, where the alloy was developed to improve long-distance telephone cables; the word is literally a promise stamped into the metal: this is the stuff that lets magnetism pass through with almost no resistance.
- recipe
- Roughly 80% nickel, 20% iron, almost no resistance to magnetism
- telegraph hero
- Wrapped Atlantic cables to speed transatlantic signals
- shielding
- Mu-metal cousins guard sensors from stray magnetic fields
- invented
- Born at Bell Labs around 1914
- heat-sensitive
- Magnetic gifts ruined by careless bending or stress
mumetal — nickel-iron alloy with 77% nickel, used for electromagnetic shielding in precision instruments since 1920s
supermalloy — nickel-iron alloy with 79% nickel and molybdenum, highest permeability alloy developed by bell labs
carpenter 49 — iron-nickel-cobalt permalloy variant used in magnetic cores and recording heads since 1940s