AGAOGULLARI Duygu Istanbul Technical University

Spoluautoři BALCI Ozge, GOKCE Hasan, DUMAN Ismail, OVECOGLU M.Lütfi

Particulate reinforced Al matrix composites (PRAMCs) have been widely used to supply the increasing demands of advanced structural and thermal applications including aircraft components, brake rotors, drums, cylinders and pistons in automobiles and brake discs in railway vehicles due to their superior properties such as light density, high strength, high specific stiffness, high elastic modulus, high wear, creep, fatigue and corrosion resistances and thermal stability compared with conventional monolithic alloys. This study reports the preparation of Al matrix composites reinforced with TiB2 particles by using a combined method of cryogenic milling (CM), cold pressing and pressureless sintering. CM was carried out using a SpexTM 6870 Freezer/Mill under liquid nitrogen, in a polycarbonate vial (22 ml) with stainless steel end caps and an impactor. The effects of TiB2 (5, 10 and 15 wt.%) content, cryogenic milling duration (10 and 20 minutes) and cryogenic milling rate (7 and 10 cycle per second) on the density, microhardness, wear resistances and microstructural properties of the Al matrix composites were investigated. After CM of powder blends, they were pressed into cylindrical preforms under 300 MPa pressure in order to obtain high green densities and were sintered at 650ºC for 5 h in a tube furnace under controlled atmosphere. Phase and morphological characterizations of the milled powders and the sintered samples were performed using X-ray diffractometer (XRD) and scanning electron microscope/energy dispersive spectrometer (SEM/EDS). Microhardness, wear and density measurements of all sintered samples were respectively conducted by Vickers indentation method, ball-on-disc test method and Archimedes method.