| 摘要 |
PURPOSE:To permit high-speed erasure by forming a recording layer of the alloy which is an alloy system where the intermetallic compd. or ordered alloy appears as the stable phase in the phase diagram and which is the alloy system where the eutectic alloy defined by the extra polation of the liquids line appears as the metastable phase and which is adjusted with the compsn. range where said eutectic alloy appears. CONSTITUTION:A reflective layer 14 made of a metal is formed on the recording layer 13. The reflective layer 14 is formed of a thin metallic film of Al, Cu, or Cr, etc. having high reflectivity and reflects a laser beam at the boundary between the recoding layer 13 and the reflective layer 14. The recording layer 13 is formed of the alloy which is the alloy system where the intermetallic compd. or ordered alloy appears as the stable phase in the phase diagram, and which is the alloy system where the eutectic alloy or deep metastable eutectic alloy defined by the extrapolation of the liquids line appears as the metastable phase and which is adjusted within the compsn. range where said eutectic alloy appears. Such deep metastable eutectic alloy includes an Al-Mg alloy, etc. contg. 40-70atom% Mg. |
