Search

In this paper, boron nitride (BN) sheets, as two‐dimensional thermal conductive fillers, were integrated into shape memory poly(aryl ether ketone) (PAEK) matrix to improve the response speed of actuators. The thermal conductivity of composites was found to be positively correlated with the content of BN sheets. Significantly, a highest in‐plane thermal conductivity of 2.66 W m−1 K−1 was obtained, which resulted in the increase of the recovery speed of the PAEK/BN actuators from 18 to 6 s. Besides, the integration of BN sheets improved the shape memory effect of PAEK matrix, including the higher shape recovery ratio (up to 99.9%) and fixity ratio (over 97%). In addition, through the assembling of four components with designed BN contents, we achieved the interesting staged shape recovery behaviors for PAEK/BN composite actuators, which enabled programmable and smart manipulations. These fabricated PAEK/BN composite actuators with rapid response and staged deformation behaviors possessed the wide utilization potential in smart devices. [ABSTRACT FROM AUTHOR]

In this work, 3.5 vol% TiB/Ti6Al4V composites with aligned TiB whiskers are synthesized by spark plasma sintering-hot extrusion (SPSHE). The effects of deformation temperature and deformation amount on the microstructure evolution and tensile properties are systematically investigated in composites. The results suggest that the dispersion of TiB whiskers is gradually improved with the deformation increasing from 30%, 50%–70%. TiB whiskers obtain a highly consistent orientation as the composite is deformed by 70%. The multiplication of more dislocations induced by TiB whiskers provides the driving force for dynamic recovery and dynamic recrystallization of the composite during SPSHE. In addition, the matrix microstructure of the composite is composed of α phase, β phase and interface L phase. The interface L phase decreases the mean free path of dislocation slip and improves the strength of the composite manipulated by SPSHE. The tensile strength (1294 ± 20 MPa) and elongation (5.0% ± 0.5%) of the composite with a deformation amount of 70% at 950 °C are well combined. According to the analysis results of the microstructure and fracture, the strengthening mechanism of the composite is the TiB load transfer strengthening effect and the matrix strengthening effects including interface L phase strengthening, fine grain strengthening, substructure strengthening and texture strengthening. [ABSTRACT FROM AUTHOR]