Evolution of TaC morphology during directional solidification of Ni, Cr, Al-TaC in-situ composite

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ÎÄÕÂÒ³Â룺99 - 103

Key words£ºcomposite£» TaC£» fibers£» crystal growth£» directional solidification

Abstract: The Ni, Cr, Al-TaC composite was directionally cast from a nickel-base alloy with a nominal mass composition of Ni-10Cr-5.0Al-13.9Ta-0.9C (mass fraction, %). The morphologies of TaC in the in-situ composite was observed with AMRAY100B SEM. TEM investigations were preformed in a JEM2000CX instrument at 150¤@kV. The experimental results show that TaC fibers are grown from the dendritic arms of the primary blocky TaC in the bottom of the directionally solidified Ni, Cr, Al-TaC sample. The longitudinal growth of TaC fibers is controlled by the pyramid growth mechanism under forced heat flow of [001] orientation. The transverse growth pattern of TaC is markedly affected by the unstable mode. The multiplicity of TaC transverse morphologies is presented.