Microstructure and mechanical properties of PZT fibres

The single fibre test was used to determine the stress–strain behaviour and the strength distribution of three commercially available PZT-5A fibres with an approximate diameter of 250 μm. One of the fibres was manufactured via an extrusion process, whereas the others were produced via similar spinning processes. All the fibres presented a non-linear stress–strain behaviour, which is apparently linked to their piezoelectric nature. The Youngʹs modulus of the fibres varied between 38 and 40 GPa. The strength distribution analysis (i.e. Weibull analysis) indicated large differences between the fibres with scale parameters varying between 49 and 68 MPa, and shape parameters situated between 4 and 12. These results were well correlated with the presence of defects in the fibres observed under a microscope. The fibres with the lowest scale and shape parameters, manufactured via a spinning process, contained large porosities and their diameter was varying along their length. In contrast, the two other fibres produced via different manufacturing processes (extrusion and spinning) presented better strength properties and a more homogeneous microstructure.