| Ti_5Si₃, was synthesized by arc melting of Ti and Si elemental powders. The synthesized Ti_5Si₃ buttons were milled and sieved up to -325 mesh size powders, which were densified using hot isostatic pressing. Microcracks in larger grains were observed for the HIPed specimens with initial powder size of -325 mesh. Six hour milling of -325 mesh powder resulted in fine grain size (about 1-2㎛ in diameter) with no microcracks after HIPing. The thermal expansion coefficients along the a and c axis were measured as a function of temperature using high temperature X-ray diffractometry. The anisotropy in the thermal expansion coefficient is believed to be one of the major causes for microcracks in larger grains. Mechanical properties, such as hardness and fracture toughness, were measured for HIPed specimens. The oxidation behaviors of consolidated Ti_5Si₃, were also investigated in terms of weight changes at elevated temperatures in air. |
|
