Superesfriamento de metais fundidos.

Abstract

This work presents a study on supercooling of pure copper by the method of elimination of catalytic sites of heterogeneous nucleation by the technique of fusion in the presence of commercial glass as flow. Samples involved by the flow were conditioned in quartz crucible and submitted to heating and cooling cycles in a furnace with resistive heating at rates of 60 K / min and 10 K / min respectively. Overheating 40K was used. Temperature control and recording were performed with a 1mm thermocouple located on the bottom of the crucible and digital and potentiametric X-t recorders. The degree supercooling was measured by the detection of the rectal sample in the solidification. Higher supercooling levels were obtained, and the maximum reached in this work was (A T :: = 27 i K), higher than those reported in the literature. The level of supercooling achieved increased with the increase in number of heating / cooling cycles. Analyzes metallography indicate homogeneity and grain refining of the sample structure with a high degree of supercooling. This demonstrates the feasibility of the technique applied here as a method of elimination of catalytic sites of heterogeneous nucleation and the efficiency of the process of imposing high degrees of supercooling to obtain refined and homogeneous structures.