Abstract: A lead material for a battery includes a metal plate made of single metal, in which the hardness of a central portion is lower than the hardness of a surface layer portion.

Abstract: A battery terminal is made of a clad material in which a first metal layer made of an Al-based alloy, a second metal layer made of a Cu-based alloy, and a third metal layer made of a Ni-based alloy are bonded to each other in a state where the first metal layer, the second metal layer, and the third metal layer are stacked in this order. The battery terminal includes a shaft portion and a flange portion that radially expands from the shaft portion, and has the third metal layer at least in an end of the shaft portion on a first side in a shaft direction in which the shaft portion extends.

Abstract: A hairspring material for a mechanical timepiece includes an alloy which contains 37.5 to 39.5% by mass of Ni, 9.2 to 9.9% by mass of Cr, 0.35 to 0.55% by mass of Ti, and 0.6 to 0.9% by mass of Be, based on the total amount of the alloy, and contains in the remainder Fe and unavoidable impurities, the alloy being an alloy containing, as the unavoidable impurities, C (carbon), Mn in an amount of more than 0% by mass but not more than 0.5% by mass and Al in an amount of more than 0% by mass but less than 0.03% by mass, the amount of the C (carbon) being limited to not more than 0.03% by mass. The hairspring material can provide a smaller variation in Young's modulus than that of conventional hairspring materials.