Study of the addition of Nb2O5 in the particulate composites with EUROFER steel through the high energy milling.

Reference	Presenter	Authors (Institution)	Abstract
03-022	Roberta Araujo Cavalcante de Menezes	Menezes, R.A.(Universidade Federal do Rio Grande do Norte); Gomes, U.U.(Universidade Federal do Rio Grande do Norte); Silva, A.S.(Universidade Federal do Rio Grande do Norte); Oliveira, L.A.(Universidade Federal do Rio Grande do Norte);	The addition of oxides, carbides or nitrides to metal matrix composites, by powder metallurgy (PM), has been studied in order to improve the properties of steels from the processing of the powders to the final sintered product. High energy milling (MAE) is an important stage of MP; in which the powders are processed in order to obtain crystallite size refinement and the formation of composite particles, in addition to a homogeneous dispersion of phases, and, consequently, composite powders exhibiting greater sintering. The changes in the parameters of the MAE process directly influence the characterization of the ground powders, as well as the properties of the final product of the PM, the sintered. EUROFER is a ferritic/martensitic steel with good mechanical properties, but its use is restricted to temperatures around 500°C due to the precipitation of chromium carbides. Studies show that the addition of oxides in EUROFER raises this working temperature. In this study, the behavior of the EUROFER Pure chip and with addition of 3%, 5% and 7% by weight of niobium pentoxide (Nb2O5) during the high energy milling process (MAE) was analyzed. The EUROFER Pure chip and with Nb2O5 were milled for 5, 10 and 15 hours, at a speed of 400rpm and relative ball/mass of 10:1 in a dry medium. They were characterized by assays of the particle size distribution, scanning electron microscopy (SEM), dilatometry, X-ray fluorescence (XRF), X-ray diffraction (XRD) analysis and the crystallite size. The results showed a refinement of the ground powders, as well as a good dispersion of the phases and formation of composite particles, through the addition of the Nb2O5 oxide to the EUROFER steel and the high energy milling.
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