AFM Analyses of 3XXX Series Al Alloy Reinforced with Different Hard Nanoparticles Produced in Liquid State

Abstract

In the present work, nanocomposites-based 3XXX series Al alloy with three different types of hard nanoparticles, including TiO2, C, and CeO2, were produced employing two techniques such as mechanical milling and stir-casting method in order to evaluate the viability of integration of the reinforcement in the Al matrix. The integration and dispersion capability of the reinforcement into the Al alloy (3xxx Series) matrix was evaluated, using a phase angle difference and surface roughness analyses by atomic force microscopy operated in both the contact mode (CM-AFM) and tapping mode (TM-AFM), respectively. The distribution profile of both rugosity and the phase angle shift was used to statically quantify the integration and dispersion of the reinforcement into the extruded samples, by using the root mean square (RMS) parameter and phase shift coupled with the events number (EN) parameter. Results from Atomic Force Microscopy (AFM) analyses were corroborated by X-ray diffractometry and scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Microhardness tests were conducted to identify the mechanical properties of the composites in the extruded condition and their correlation with the microstructure. A close relationship was found between the microstructure obtained from the AFM and X-ray diffractometry (XRD) analyses and mechanical properties. Among all, the C reinforcement produced the major changes in the microstructure as well as the best integration and dispersion into the Al-alloy coupled with the best mechanical properties.

Statistical and Microstructural Analyses of Al–C–Cu Composites Synthesized Using the State Solid Route

“…The increase of the mechanical properties of the composite with the milling time is related to several strengthening mechanisms: grain size refinement, powder surface area increases, crystallite size reduction, integration and dispersion of the reinforcing particle into the Al matrix, and strain hardening, among others [ 25 , 26 ]. From the results, we observed that an increase in sintering temperature and time also favored the precipitation and growth of second phases (e.g., Al 4 C 3 or AlCu,); this effect was observed in the contour plot for the yield stress and microhardness tests when the sintering time was increased from 1.5 to 3 h. The presence of these second phases has been previously reported in other works on X-ray diffraction analysis carried out on samples with C and Cu content [ 27 , 28 ]. The most significant effect was observed in the microhardness tests for 3/100 samples, where a change in sintering change from 1.5 to 3 h (at 600 °C hold) resulted in an increase of approximately ≈ 23% in the microhardness value; while, for the yield stress tests (under the same conditions), it presented an increase of ≈ 10% (see Figure 4 a,b).…”