フェルミ面
The Fermi surface of the pure metal is constructed under the assumption that the wave vector k of the Bloch electron is a good quantum number. But alloying destroys the periodicity of the lattice potential and thus results in scattering of the Bloch electron. The wave vector k changes upon scattering of the Bloch electron and can no longer be taken as a good quantum number. In spite of such fundamental difficulties, experimental and theoretical works have provided ample evidence that the concept of the Fermi surface and Brillouin zone is still valid even in concentrated crystalline alloys