To obtain a heat sensor functioning as a safety device preventing a user from continuously using an electric apparatus until a dangerous state, by joining a first metal of at least one selected from Fe, Ti, Ni, Nb and an alloy essentially consisting of these metals to a second metal of either Al or an alloy essentially consisting of Al.
A heat sensor 1 is formed by joining a first metal 10 of at least one selected from Fe, Ti, Ni, Nb and an alloy essentially consisting of any one of the metal elements to a second metal 20 of either Al or an alloy essentially consisting of Al. When the heat sensor 1 is heated, for instance, to a temperature range by a surrounding heat source, a fragile intermetallic compound is formed because of a counter diffusion of the metal elements of the first metal 10 and second metal 20. The fragile intermetallic compound is, e.g. FeAl2 or the like when the first metal 10 is Fe or essentially consists of Fe. If the fragile intermetallic compound is generated by a predetermined amount or more, the sensor automatically breaks, thereby shutting electric connection to the heat source.
SAKON SHIGETOSHI
HAMADA TADASHI
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