A new mechanism of grain selection in spiral selector: The competitive growth between the entrance grains

Abstract

The grain selection in spiral selector is investigated systematically by experiments and simulations. To simplify the grain selection in spiral selector, a novel 2-D zigzag selector is designed to replace the 3-D spiral selector. It is found that the grain, locating at the selector entrance and close to the initial rotation direction, is apt to grow into single crystal structure. Besides，the effect of competitive growth between the entrance grains on grain selection cannot be ignored. According to the experimental and simulated results, the grain selection in spiral selector is dominated by the grain location and the competitive growth, which is first proposed as “the competitive growth between the entrance grains” mechanism. The new mechanism is different from the generally accepted understanding that the grain selection in spiral selector is random and dominated by “geometry blocking” mechanism.