INFLUENCE OF THE INCLINATION OF THE FURNACE IN THE POSITION OF THE CET

A. E. ARES; S. F. GUEIJMAN; M. V. OKSENIUK; C. E. SCHVEZOV

Beijing, China

Conferencia; THE 16th INTERNATIONAL CONFERENCE ON CRYSTAL GROWTH (ICCG-16); 2010

ICCG-16

In a solidification process, the microstructure depends on the alloy characteristics and it is mainly a function of the temperature evolution ahead of the solid/liquid interphase. Among several phenomena occurring during solidification, like solute segregation or morphology stability, one of the most important phenomena is the dendritic growth. In dendritic investigation, the most important parameters are the primary, secondary and tertiary arm spacings due to the influence on mechanical properties. An efficient method of examining the dendrite arms evolution is related to the application of steady-state directional solidification with imposed growth rate, V, and thermal gradient, G, at solid/liquid interphase. In this work, experiments were performed under unidirectional solidification in a device cooled with water, and Zn-1%Al and Zn-2%Al (wt%) alloys were solidified in a vertical upward (0 degrees) and inclined at 30  and 45  to the vertical. We determined the position of the transition from columnar to equiaxed structure (CET) through macro-analysis, and significant thermal parameters by recording temperature-time data. The main results obtained in samples of 120 mm-length and (22 ± 1) mm-diameter are: a) the transition occurs in a zone of about 10 mm or greater, where coexist columnar and equiaxed grains, b) in the three directions, where CET occurs the temperature gradient reaches critical values, c) the angle of inclination of the columnar grains with the longitudinal axis of the sample coincides approximately with the angle of the furnace, d) the thermal parameters (cooling rates, Liquidus and Solidus interphase velocities and temperature gradients) at the instant of the CET were measured and compared with previous results of samples solidified vertically upward.