Avaliação da influência do tratamento térmico T6 na liga A380 com adição de carbetos de nióbio e tixoconformada

Abstract

Composite materials, consisting of an aluminum matrix, have gained prominence in the industry due to characteristics such as high specific strength, stiffness, wear resistance, and improved properties at high temperatures compared to other alloys. This study focuses on the metal matrix composite, formed by the A380 alloy reinforced with niobium carbides (NbC) in its cast and thixoformed version. The objective of this research was to perform the T6 heat treatment, which involves solutionizing at 530°C, with varying sample retention times of 3 hours in the first batch and 6 hours in the second batch, followed by artificial aging treatment at 180°C for 3 hours, and evaluate their behavior regarding hardness, corrosion resistance, and microstructural changes. To obtain these data, Rockwell B Hardness tests, Electrolytic corrosion tests, and analysis by Optical Microscopy and Scanning Electron Microscopy (SEM) were performed. It was observed that the longer the samples remained in the solutionizing treatment, the lower the values obtained for hardness, except for samples without the addition of NbC from batch 1, which showed a significant increase in hardness compared to the standard batch (without treatment). In parallel, the samples followed the same behavior as hardness, becoming more susceptible to corrosion with increasing sample retention time in the solutionizing heat treatment, with untreated samples showing the lowest annual corrosion rates. The samples with better refinement and phase distribution, impacting mechanical properties, were the cast samples from batch 1. Even with the refinement in thixoformed samples, the thixoforming process resulted in recrystallization of the alloy, reducing the material's hardness.