Papers by Keyword: Interface Region

Abstract: Effect of the microstructural homogeneity of 0.5 BaTiO₃ - 0.5 KNbO₃ (0.5BT-0.5KN) solid solution ceramics on the dielectric and piezoelectric properties was investigated. Microstructure of a sample prepared by a conventional sintering method was homogenous, and the room temperature crystal structure was assigned to cubic Pm3m symmetry and therefore the sample was paraelectric. On the other hand, microstructure of samples prepared by a two-step sintering method was inhomogeneous, that is, it was made of BT and KN grains. The large electric field piezoelectric constant d₃₃* increased with increasing interface area.

Abstract: Barium titanate (BaTiO3, BT) - potassium niobate (KNbO3, KN) solid solution system (0.5BT-0.5KN) ceramics with various microstructures were prepared by conventional sintering method and two-step sintering method using BT and KN nanoparticles. Their microstructures were investigated using X-ray diffraction (XRD) measurement and scanning electron microscopy (SEM), and it was confirmed that two ferroelectric phases, i.e., BT-rich tetragonal and KN-rich orthorhombic phases, always coexisted for all ceramics, which suggested that 0.5BT-0.5KN ceramics had “pseudo-morphotropic phase boundary (MPB)” structure. Thus, the control of the interface area between two phases was important to enhance piezoelectric property. Finally, their piezoelectric property was measured, and the apparent piezoelectric constant d33* increased with increasing interface area.

Abstract: Diffusion in the interface regions of lightweight heatproof quality titanium and titanium/aluminum alloys was investigated. We studied the diffusion of aluminum from intermetallide to titanium alloy. The concentration of other chemical elements and microhardness has been measured in diffusion region formed in the solid titanium alloy. The interface region includes a transition zone from the initially solid Ti-alloy and the molten TiAl-Nb intermetallic substrate. The width of the interface region after diffusion bonding is 45-60 µm. The titanium content decreases and aluminum content increases starting from surface up to 120-150 µm in depth in solid titanium alloy. As a result of diffusion, the intermetallic Ti3Al thin layer was formed in the transition zone in the Ti-alloy substrate. The microporosity was also formed in the interface region.