In this paper, a self-propagating high-temperature combustion synthesis with the pseudo-hot isostatic pressing process(SHS/PHIP) was employed to fabricate high-pure Ti3AlC2(U 240 mm). In addition, the first principle with quasi-harmonic approximation was applied for the thermodynamic properties' investigation of Ti2AlC and Ti3AlC2, including Gibbs free energy, enthalpy, and entropy.With temperature increasing, Gibbs free energy increases,but enthalpy and entropy decrease. The present work provides the theoretical proof for the synthesis mechanism of Ti3AlC2 by SHS/PHIP.
In this paper, phase composition of the Mn+1-AXnphases by self-propagating high-temperature synthesis(SHS) was determined using Ti, Cr, Al, and carbon black as raw materials. And, phase composition and microstructures of the Mn+1AXnphases-contained bulk by SHS with the pseudo-hot isostatic pressing(SHS/PHIP) were investigated in Ti–Cr–Al–C systems raw materials. Rietveld XRD refinement was introduced to study the lattice parameters and phase composition of the resultant phases from the SHSed and SHS/PHIPed samples. Ti2 AlCx,Ti3AlC2x, and Cr2 AlCxby SHS were detected in the Ti–Cr–Al–C systems, as well as the binary carbide of TiC and intermetallics. The mechanical properties of the synthesized bulk samples were determined, exhibiting a high strength and toughness compared with the typical monolithic Mn+1AXnphase ceramics. It is indicated that the samples prepared by SHS/PHIP are identified to be a strategy for improving the mechanical properties of monolithic Mn+1AXnphase.
Guo-Bing YingXiao-Dong HeShan-Yi DuChun-Cheng ZhuYong-Ting ZhengYu-Ping WuCheng Wang
TiC–TiB2 /Cu composites were prepared by self-propagating high-temperature synthesis with pseudo hot isostatic pressing using Ti, B4 C, and Cu powders. The compressive deformation of the composites at high temperature was investigated. It is found that the maximum compressive strength decreases with the increase of temperature and Cu content. The deformation of the composites includes the steps of elastic, stable rheology, and inaction. The maximum strain is in the range of 5 %–10 %. Before fracture, TiC–TiB2 /40Cu becomes drum-shaped at 1123 K; however, TiC–TiB2 /20Cu only has a brittle fracture along the axial direction of 45°. The results show that the compressive strength of TiC–TiB2 /Cu decreases from 823 to 1223 K. However, the maximum compressive strength of TiC–TiB2 /20Cu reaches 1850 MPa at 823 K, which predicts that this series of composites could be applied to high-temperature compressive materials.
In this paper, Ti–Cr–Al–C materials were investigated by self-propagating high-temperature synthesis(SHS) according to the experimental study and numerical simulation results. The highest adiabatic combustion temperature Tadof 2,467.45 K indicates that the2Ti–0Cr–Al–C is the highest exothermic reaction system in the Ti–Cr–Al–C system. The adiabatic combustion temperature decreases with the increase of the Cr content. And a higher exothermal reaction would result in higher porosity which is induced by the high temperature and pressure of C reducing atmosphere and Al vapor. Combustion characterization of the products shows that the geometrical alternating layers result in the high exothermal reaction and flame-front propagating velocity. The higher the Tadis, the thinner the layer is. To demonstrate the process of the microscopic characterization and show the detailed combustion process closed to the experimental observations, the flame-front propagating velocity and temperature distribution were simulated numerically.
Guo-Bing YingXiao-Dong HeShan-Yi DuYong-Ting ZhengChun-Cheng ZhuYu-Ping WuCheng Wang