Thermal and solutal influences of continuous fibers on matrix dendrite growth in composite materials

Numerical simulation was applied to evaluate the thermal and solutal influences of fibers on the dendrite growth of matrix alloy reinforced with continuous fibers. The results of temperature and solute distribution, and dendrite tip undercooling and tip radius were compared with experimental data obtained from directional solidification studies for polyvinylidene fluoride, Pyrex glass, and copper fiber reinforced succinonitrile-acetone alloy composites. In the polyvinylidene flouride fiber/pure succinonitrile composites, dendrite in the composite region grew behind than that in the bulk region, and in the direction of the heat flow. However, dendrite between copper fibers grew faster than that in the bulk region. A computer simulation revealed that a difference in thermal diffusivity influences the thermal distribution of specimens and the apparent dendrite tip location. The gap in dendrite tips between the composite and bulk regions increased as the composition of acetone increased or the fiber interstices became smaller. Numerical analysis revealed that tip composition and undercooling increased as the fiber interstices became smaller than the primary dendrite arm spacing. The constraint of growth on the secondary arm and the change of dendrite morphology were also shown in the analysis.