Xianquan Jiang

Piezoelectric and dielectric properties of lead-free 0.96(K0.48Na0.535)0.96Li0.04Nb1-xSbxO3-0.04CaZrO3 ceramics with rhombohedral–orthorhombic phase boundary

ABSTRACT Lead-free 0.96(K0.48Na0.535)0.96Li0.04Nb(1-x)SbxO3-0.04CaZrO3 ceramics were prepared by a conventional solid-state reaction method. The crystal structure of the ceramics was found transforming from an orthorhombic phase to a rhombohedral phase with the increase of Sb content. Furthermore, a rhombohedral-orthorhombic phase boundary was determined in 0.03 ≤ x ≤ 0.05, near which the ceramics exhibited relatively high piezoelectric properties, with maximum values of d33 ∼ 213 pC/N and kp ∼ 0.37 at x = 0.03. Our results suggest that Sb may play an important role in the construction of phase boundary as well as the improvement of piezoelectric activity for (K,Na)NbO3-based piezoelectric ceramics.

Hot Deformation and Processing Map in an Mg-Zn-Mn-Y Alloy

In recent years Mg-Zn-Y series alloys have drawn significant interest due to their superior mechanical properties. The addition of yttrium to the Mg-Zn alloy leads to the formation of a special phase (Mg12YZn) with a long-period stacking ordered (LPSO) structure, which plays an important strengthening role. The main objective of this study was to identify the deformation mechanisms of LPSO phase in an as-extruded yttrium-containing magnesium alloy. On the other hand, the successful manufacturing of magnesium alloy components requires the optimal hot working parameters. The processing map is an effective tool which can be used to pinpoint the optimal processing regions and the instability regions which should be avoided. Another objective of this study was thus to evaluate the hot deformation behavior of a Mg-Zn-Mn-Y alloy via isothermal compression testing at different temperatures and strain rates. The processing maps were constructed and the optimal hot processing conditions were identified.