Influência da adição de Nb e Cr nas propriedades microestruturais e mecânicas de uma liga CuAlMn

Abstract

This work investigates the effects of chromium (Cr) and niobium (Nb) additions on the microstructural, mechanical, electrochemical, and functional properties of Cu–Al–Mn shape memory alloys. The alloys were produced by induction furnace melting, followed by homogenization heat treatment and quenching, and characterized using techniques such as optical microscopy, scanning electron microscopy, corrosion resistance testing, and microhardness measurements. The results demonstrate that Cr and Nb promote significant grain refinement, the formation of Al–Cr- and Al–Nb-rich precipitates, an increase in the fraction of 18R martensite, and improvements in the structural stability of martensite. Microhardness tests and X-ray diffraction (XRD) confirmed hardening and changes in phase equilibrium, while energy-dispersive spectroscopy (EDS) validated the incorporation of the alloying elements. Electrochemical analyses showed that the isolated additions of Cr and Nb increase corrosive activity; however, when combined, these elements exhibit a synergistic effect, strengthening the passive film and improving corrosion resistance. The observed increase in electrical resistivity and in the e/a value reinforces the influence of these elements on the electronic behavior and martensitic stability. Thus, Cr and Nb demonstrate strong potential to enhance mechanical reliability, structural and chemical integrity, and to ensure the stability of the functional properties of the alloy.