Caracterização de ligas Fe-Ni processadas por metalurgia do pó: influência dos parâmetros nas propriedades mecânicas (dureza).

Abstract

Powder metallurgy becomes an important process for manufacture of parts with complex geometry, making it more feasible. The big challenge is to minimize the damage caused by the residual porosity by this procedure. The purpose of this study was to characterize and evaluate the influence of temperature on the mechanical properties (hardness) of alloy Fe-70% Ni 30%, used in electronics and structural materials for automotive engine parts, being produced by powder metallurgy (PM). The Fe-Ni alloys were produced from powders compressed uniaxially cold pressed and sintered, yielding material with near theoretical density for this class of alloys. Simulations were conducted to predict the phases present in the software Thermocalc. Then the specimens were subjected to a sintering temperature of 1,000°C and 1,100°C to evaluate the increase in hardness by varying the temperature. The microstructure was investigated by Scanning Electron Microscopy (SEM) view a possible decrease in the amount and size of pores with increasing temperature and energy dispersive spectrometry X-ray (EDX) characterizing the presence of martensite. Images of atomic force microscope (AFM) were used to illustrate the martensite. Were raised hardness profiles of samples in a durometer ITDPMD-130, showing that simply increasing sintering temperature resulted in an increase of 12% in its hardness.