3. The Fe—Cr alloy according to 1. or 2. having a sheet thickness of 200 μm or less.

4. A method for producing a Fe—Cr alloy, comprising:

• • rolling a slab having a chemical composition containing (consisting of), by mass %,
  • C: 0.020% or less,
  • Si: 0.01% to 1.5%,
  • Mn: 1.0% or less,
  • P: 0.040% or less,
  • S: 0.010% or less,
  • Cr: 16.0% to 30.0%,
  • Al: 2.0% to 6.5%,
  • N: 0.020% or less, and
  • Ni: 0.50% or less, with the balance being Fe and inevitable impurities to obtain a sheet material having a final sheet thickness;
  • subjecting the sheet material to siliconizing treatment by a thermal CVD method to obtain a Fe—Cr alloy having a Si content of more than 1.5 mass % and 10.0 mass % or less and satisfying the following formula (1):
    14.0≤% Si+1.15×% Al+0.35×% Cr ??(1)
    where % Si, % Al, and % Cr indicate a Si content, an Al content, and a Cr content, by mass %, respectively in the chemical composition of the Fe—Cr alloy.

5. The method for producing a Fe—Cr alloy according to 4., wherein the chemical composition of the slab further contains, by mass %, at least one selected from the group consisting of