単ロール超急冷凝固法における冷却速度の光学的測定法

抄録

  Optical Measurement was examined to measure the cooling rate of the thin ribbon produced by splat cooling of single roller. The temperature measurements of metal surface were made by the surface radiance in the range of IR wave length, and high speed PIN Si photodiode was used to measure the radiance. The cooling rate (V) of the thin sample is proportional to the rotational speed (R) over a range from 500 to 4000 rpm, and it is V = 2.42 × 10²R in Fe-C-P system alloy and is V = 2.20 x 10²R in Fe-Ni-B system alloy. The critical cooling rate of amorphous ribbon is about 2.1 × 10⁵∼2.4 × 10⁵ K/s in Fe-C-P system alloy and is about 8.3 × 10⁵∼8.4 × 10⁵ K/s in Fe-Ni-B system alooy, and those critical cooling rates change the value depending on the composition of the alloy. This optical measurement may be very useful to determine the cooling rate of the sample moving at high speed, by non-contact measurement.