FINE GRAIN RARE EARTH ALLOY CAST STRIP, PREPARATION METHOD THEREOF, AND A ROTARY COOLING ROLL DEVICE

摘要

An alloy cast strip includes grains having R₂Fe₁₄B-type compound as main phase, where R denotes a rare earth element, Fe denotes iron, and B denotes boron. The grains include non-columnar grains having an aspect ratio in a range from 0.3 to 2 and columnar grains having an aspect ratio equal to or larger than 3. A ratio of an area of the non-columnar grains to a total area of the grains is equal to or larger than 60% and a ratio of a number of the non-columnar grains to a total number of the grains is equal to or larger than 75%. A ratio of an area of the columnar grains to the total area of the grains is equal to or smaller than 15% and a ratio of a number of the columnar grains to the total number of the grains is equal to or smaller than 10%.