Abstract
The difference in the grain refining capacity of Al-Ti grain refiners with and without TiC is examined.
As a result of experimental investigations by EPMA, X-ray diffraction analysis, electrical conductivity measurement and grain counting for cast samples prepared under various thermal conditions, the following conclusions were obtained;
(1) TiC particles are effective in refining Al grains, particularly when high content of Ti is dissolved in Al melt.
(2) TiC particles are fairly stable in Al melt but decompose gradually during isothermal holding. The rate of decomposition is strongly temperature dependent.
(3) TiAl3 particles can act as the nucleation center for Al when they exist in the liquid but the rate of dissolution of these particles is much faster than the rate of decomposition of TiC.
(4) The refinement due to the crystal-multiplication can be promoted by the existence of Ti in solution in certain freezing conditions.
