DIRECTIONAL SOLIDIFICATION STUDIES OF METALLIC MATRIX FIBROUS COMPOSITES

ARES, ALICIA;; RIOS, CARLOS; ;; ELVIO DE NAPOLE GREGOLIN;; CARAM, RUBENS; SCHVEZOV, CARLOS

Light Metals 2004

Alton T. Tabereaux, editor. A publication of the Minerals, Metals, & Materials Society.

Lugar: Charlotte, North Carolina. USA.; Año: 2004; p. 869 - 875

It has been seen recently a progressive increase in the research of new techniques and processes for obtaining metal matrix composites (MMC). The subject of this paper is to study the structure of Al-5%wtSiO2 fiber composite during directional solidification, due to its excellent mechanical properties and light weight. The columnar-to-equiaxed transition (CET) was observed in the samples directionally solidified from the chill zone under different solidification conditions.  The transition occurs when the gradient in the liquid ahead of the columnar dendrites reaches values between -2.70 °C/cm and -1.15 °C/cm and the growth velocities reach values between 0.04 cm/s and 0.25 cm/s.  The microstructure obtained is analyzed taking into account the characteristics of the alloy and the temperature profiles at the solidification interface.  The following tests were carried out on the composite: EDS, Vickers micro-hardness and optical microscopy. The results of the analysis are compared with those obtained in Al-Si  and Al-Si-Cu alloys.