Effect of varying TiB2 reinforcement and its ageing behaviour on tensile and hardness properties of in-situ Al-4.5%Cu-xTiB2 composite

The objective of this study is to understand the suitability of mixed salt route using stir casting technique to fabricate in-situ Al-4.5%Cu-xTiB(2) (x = 3, 6, 9 and 12 wt %) composites. The mechanism behind titanium/boron-based phase evolution in Al-Cu alloy has been enlightened first time, particularly its strong influence over mechanical behaviour was examined. The in-situ TiB2 reinforcement particles were prepared by the exothermic reaction of K2TiF6 and KBF4 salts in melted aluminium copper alloy which improves the hardness, yield, and tensile strengths to the extent of similar to 89 VHN, similar to 236 MPa and similar to 295 MPa, respectively. Preliminary microstructural evolution was analysed and discussed through optical microstructures and proposed mechanism. The composites were characterized carefully with the help of field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) to know the morphological details and TiB2 distribution in the aluminium matrix composite (AMC) microstructure. In support with electron microscopic observations, the X-ray diffraction (XRD) and Electron Probe Microscopic Analysis (EPMA) were also performed. To further enhance the mechanical properties, T6 heat treatment (HT) was done. During the HT process, the composites were solutionized at 540 degrees C for two hours followed by water quenching. After that, artificial ageing was carried out at 170 degrees C with varying durations of 5, 10, 15, 20, and 25 h and post-ageing effect on the mechanical properties were recorded. Composites were thermally characterized through differential scanning calorimetry (DSC) to learn the precipitation kinetics and compared with alloy chosen. (C) 2019 Elsevier B.V. All rights reserved.