Lidia Lityńska

Zirconia matrix–tungsten carbide particulate composites manufactured by hot-pressing technique

Zirconia matrix composites with tungsten carbide inclusions were obtained by hot pressing at 1400°C for 40 min. The carbide particle content was changed from 10 to 50 vol.%. All the samples achieved densities higher than 98% of the theoretical value. Elastic properties were measured by ultrasonic methods. Hardness and fracture toughness were estimated by Vickers indentation technique. The microstructure of the composites was determined by TEM observations.

TEM analysis of the interfaces between the components in magnesium matrix composites reinforced with SiC particles

Abstract A microstructural analysis of the interfaces between the components of cast composites based on magnesium and magnesium alloys (MgAl8, MgZn6 and MgRE3; RE: rare-earth elements) reinforced with SiC particles is presented. Transmission electron microscopy (TEM) investigations allowed to establish the adhesive character of the bonds between the SiC particles and Mg matrix as well as MgAl8, MgZn6 matrix alloys, while the composites based on Mg alloys containing rare-earth elements exhibited a reaction layer between the components. Occasionally, the interfaces between the components contained precipitates derived from the instability of the conditions or parameters of the production processes. Energy-dispersive spectrometry and electron diffraction analyses allowed to identify the precipitates as the SiO2, MgO and Fe-containing compounds.

The microstructure of melt spun Ti–Ni–Cu–Zr shape memory alloys

Abstract NiTi base shape memory melt spun ribbons with a high substitution of Ni by Cu and Ti by Zr have been analysed. Depending of the chemical composition of the alloy, the ribbons are crystalline or amorphous. Transmission electron microscopy (TEM) studies in the as-cast state and after crystallization indicated that in the as-cast state the Ti 40 Ni 25 Cu 25 Zr 10 ribbons are constituted of two phases (Ti 2 Ni+amorphous phase) whereas the Ti 40 Ni 35 Cu 15 Zr 10 ribbons are fully amorphous and are single phase after crystallisation with a B2 structure. High resolution electron microscopy (HREM) observations have shown that the crystalline/amorphous phase interface is highly wavy even at the nanometric scale and that the B2 particles are single ordered domains.

Particulate Composites of TZP-Chromium Oxide and TZP-Chromium Carbide; Microbeam Investigations

Mechanical properties and microstructure of hot-pressed zirconia-based composites containing additions of chromium carbide or chromium oxide particles were investigated. The composites showed significantly higher elastic properties, hardness and fracture toughness compared with the pure matrix. The microstructure of the materials was investigated using scanning and transmission electron microscopy as well as energy-dispersive X-ray spectrometry.