A study on the Formation Characteristics of TiAl3 Intermetallic Composites and their Elevated Temperature Properties
|Keywords:||鈦鋁介金屬;差式掃描熱量卡計;熱重分析儀;TiAl3 intermetallic compound;DSC;TGA|
In the present article, TiO2 reinforced Aluminum alloy (A356) composite was successfully fabricated by squeeze casting. Furthermore, the composite employed heat treatment was transformed to an intermetallic matrix composite by in-situ synthesis of Al2O3 reinforcement and TiAl3 matrix. According to the differential scanning calorimeter (DSC) analysis, it was found that there were two mechanisms in the chemical reaction between TiO2 and Al while the temperature was over the eutectic point of aluminum alloy (A356). One was alumina, and the other was TiAl3.Correspoundlly, the former was conducted by one dimensional diffusion control, but the latter was a first order reaction. For the oxidation test, the Al2O3/TiAl3 specimens were kept in oxygen atmosphere under 7000C ,8000C and 9000C respectively, the results illustrated that the rate of oxidation between initial state and final state was significantly different.Further observation showed that they were caused by a transformation from a transition state θ-Al2O3 to a stable state α-Al2O3. Alternatively, for the compressive strength under various temperatures, the results showed that the specimens of TiO2/Al composite at 4000C were lower than that at room temperature due to the matrix soften, from 525MPa reduced to 275MPa. On the contrary, the specimens of Al2O3/TiAl3 composite just slightly reduced to 500MPa from 550MPa, and hence possessed good performance at higher temperature.
|Appears in Collections:||Thesis|