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This study investigates the damping properties of Cu–Al–Mn shape memory alloys (SMAs) with various chemical compositions and the effects of the addition of quaternary alloying elements Ag and Nb on the microstructure, martensitic transformation behavior, and damping capacity of SMAs. Compared to other Cu–12Al– x Mn (x = 4–7 wt%) SMAs, Cu–12Al–5Mn has a more significant inherent and intrinsic internal friction (IF PT + IF I) peak above room temperature. The addition of Ag or Nb to Cu–12Al–5Mn reduced the grain size, thereby increasing the hardness of the alloys; however, the damping capacity and temperature of the IF PT + IF I peak decreased simultaneously. The addition of Ag to Cu–12Al–5Mn significantly reduced the damping capacity (IF PT +IF I peak) because of the notable decrease in the amount of transformed martensite. Moreover, the addition of Nb to Cu–12Al–5Mn caused the AlNb 3 phase to precipitate, limiting the mobility of the martensite variant interfaces and slightly decreasing the damping capacity (IF PT + IF I peak). Among the Ag- and Nb-doped Cu–12Al–5Mn SMAs, Cu–12Al–5Mn–1 Nb showed not only a significantly higher hardness but also a higher IF PT + IF I peak, with tan δ exceeding 0.01 at approximately 50 °C. [Display omitted] • In Cu-based SMAs, damping capacity depends on microstructure and the volume fraction of the transformed martensite. • Alloying elements with different mechanisms affect the damping performance of Cu-based SMAs. • In Cu-based SMAs, both damping capacity and mechanical strength improve by optimizing chemical composition. [ABSTRACT FROM AUTHOR]

Abstract: The phase equilibria in the Co–W–V ternary system were experimentally investigated by optical microscopy (OM), electron probe microanalysis (EPMA) and X-ray diffraction (XRD) on the equilibrated alloys. Three isothermal sections of the Co–W–V ternary system at 1100°C, 1200°C and 1300°C were determined, and no ternary compound was found in this system. In addition, a novel phenomena induced by the liquid phase separation in the Co–W–V alloys was firstly discovered, suggesting that a stable liquid miscibility gap exists in the Co–W–V ternary system. The newly determined phase equilibria and firstly discovered phase separation phenomena in the Co–W–V system will provide important information for the development of Co–W based alloys. [Copyright &y& Elsevier]

Abstract: A statistical second-order two-scale (SSOTS) method is established in a constructive way for predicting the thermomechanical properties of statistically inhomogeneous materials. For this kind of composite materials, the complicated micro-characteristics of inclusions, including their shape, size, orientation, spatial distribution, volume fraction and/or material properties and so on, lead to changes of the macroscopic thermomechanical properties, such as stiffness, coefficient of thermal expansion and strength of material. In this paper, a statistical model at an arbitrary position of the composite material is defined to represent the microstructure of the statistically inhomogeneous media at first. And then, the statistical second-order two-scale analysis formulation is derived. Finally, the numerical results for some statistically inhomogeneous composites are calculated by SSOTS algorithm, and compared with the data by experimental and theoretical methods. [Copyright &y& Elsevier]

The influence of Gd element and solution treatment on the microstructure of AZ31 alloy was investigated in this paper. The microstructure and phase composition were characterized by OM, SEM, EDS and XRD. The results indicate that Mg 17 Al 12 eutectic phase, scattered along the grain boundary, is suppressed effectively with Gd addition and the acicular Al 2 Gd superlattice with lamellar distribution is formed. Furthermore, the grain size of AZ31 alloy is also refined with Gd addition. In the subsequent process of solution, the migration and growth of Al 2 Gd phase conforms to Ostwald Ripening Theory. The morphology of Al 2 Gd phase becomes granular and scatterd in matrix uniformly after solution for 16 h at 813 K. [ABSTRACT FROM AUTHOR]

Abstract: Pb(Zr0.9Ti0.1)O3 pyroelectric thick films adding various amounts of the sintering aids Bi2O3–Li2CO3 have been deposited on the substrates Al2O3 by the screen-printing process, and the dependence of microstructure, dielectric and pyroelectric properties on the content of sintering aids has been studied. When the amount of Bi2O3–Li2CO3 increases from 0wt% to 5.4wt%, the sintering temperature of the thick films decreases from 1100°C to 900°C, and the grain size and the lattice constant decrease either, but the density and the dielectric constant increase. The Pb(Zr0.9Ti0.1)O3 thick film with 5.4wt% of Bi2O3–Li2CO3 sintered at 900°C has the maximum pyroelectric coefficient 10.51×10−8 C/cm−2 K−1 and the highest figure-of-merit 10.58×10−5 Pa−0.5. [Copyright &y& Elsevier]