VARIABLE SPECTRAL REFLECTIVITY ALLOY AND RECORDING MATERIAL

摘要

PURPOSE:To provide a variable spectral reflectivity alloy which can maintain partially different spectral reflectivities at the same temp. by consisting said alloy of a copper alloy contg. Ge. CONSTITUTION:The alloy of this invention is subjected to a heating and cooling treatment in a solid phase to have at least >=2 kinds of the spectral reflectivities at the same temp. and can vary reversibly the spectral reflectivities. More specifically, this alloy has the phases of different crystal structures in at least two temp. regions in the solid phase state. The spectral reflectivity varies with the state in which the high-temp. phase out of said phases is quickly cooled and the standard state without quick cooling. The spectral reflectivity is reversibly changed by the heating and quick cooling in the temp. region of the high- temp. phase and the heating and cooling in the temp. region of the low-temp. phase. The copper alloy consisting of 20-28wt% Ge and the balance Cu is preferable as the above-mentioned alloy. The alloy compsn. having eutectoid transformation is preferable for this alloy. A large difference in the spectral sensitivity is obtd. with such alloy by the quick cooling from the high temp. and without quick cooling.