Search

Niobium aluminum carbide ( Nb4 AlC3), as a member of the MAX phases, can retain its stiffness and strength up to over 1400°C, however, the strength at room temperature is relatively low. In this work, Nb5( Si, Al)3 was used to strengthen Nb4 AlC3. Nb4 AlC3- Nb5( Si, Al)3 composites with different amount of Nb5( Si, Al)3 were synthesized from the elemental powders by in situ hot-pressing/solid-liquid reaction synthesis process. The RT flexural strength was significantly improved from 370 MPa of monolithic Nb4 AlC3 to 432 MPa of Nb4 AlC3-15 vol% Nb5( Si, Al)3 composite without the degradation of its high-temperature mechanical properties. While a slightly decrease in fracture toughness occurs with the increment of Nb5( Si, Al)3 content. Meanwhile, Transmission electron microscopy ( TEM) observations reveal that the interfaces between Nb4 AlC3/ Nb4 AlC3, Nb4 AlC3/ Nb5( Si, Al)3, and Nb5( Si, Al)3/ Nb5( Si, Al)3 are free of amorphous layers, which is also beneficial to its high-temperature mechanical properties. [ABSTRACT FROM AUTHOR]

In this study, a well-dispersed γ-Y2Si2O7 ethanol-based suspension with 30 vol% solid loading was prepared by adding 1 dwb% polyethylene imine dispersant, which allows feeble magnetic γ-Y2Si2O7 particles with anisotropic magnetic susceptibility to rotate in a 12 T strong magnetic field during slip casting, resulting in the development of a strong texture in green bodies. Pressureless sintering gives rise to more pronounced grain growth in the textured sample than in the untextured sample prepared without the magnetic field due to the rapid migration of the grain boundaries of the well-oriented grains, which was revealed by constant-heating-rate sintering kinetics. It was found that the use of two-step sintering is very efficient not only for inhibiting the grain growth but also for enhancing the texture. This implies that controlled grain growth is crucial for enhancing texture development in γ-Y2Si2O7. [ABSTRACT FROM AUTHOR]