Effect of processing parameters on microstructures and mechanical properties of rapidly solidified AlFeVSi hot-extruded product
(School of Materials Science and Engineering,
Central South University, Changsha 410083, China)
Central South University, Changsha 410083, China)
Abstract: Rapidly solidified blanks of Al-8.5Fe-1.3V-1.7Si aluminum alloy were prepared by using two methods of cold-isostatically pressing of atomized powder and spray deposition of melt metal. Influence of processing parameters, such as extrusion ratio, aspect ratio of cross section of extruded product, extrusion temperature and heating time on microstructures and mechanical properties of rapidly solidified AlFeVSi aluminum alloys was studied by means of optical microscopy, X-ray diffractometry, transmission electron microscopy and measurement of tensile properties. Suitable processing parameters were selected to extrude spray deposited blanks into large size pipes. The results show that the effect of extrusion ratio and aspect ratio on microstructures and mechanical properties of rapidly solidified AlFeVSi aluminum alloys can be evaluated by calculating parameter Rs, and the value of Rs ought to be at least close to 6 in order to obtain high performance extruded product with good binding state. With the increase of extrusion temperature and heating time, the dispersed Al12(Fe,V)3Si particles congregate and coarsen in α(Al) matrix，and the coarse lumpish θ-Al13Fe4 phase appears in the alloy extruded above 500℃. Therefore, lowering extrusion temperature and shortening exposure time at high temperature through multistage heating are of benefit to changing microstructures and improving mechanical properties of the extruded product. The large size pipes of spray deposited AlFeVSi aluminum alloy extruded at 490℃ in the condition of Rs being close to 6 and multistage heating have excellent tensile strength and plasticity at room and higher temperature.
Key words: spray deposition; extrusion; rapid solidification; heat-resistant aluminum alloy