Kinetics and numerical simulation of self-propagating high-temperature synthesis in Ti–Cr–Al–C systems

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.

Formation of M_(n+1)AX_n phases in Ti–Cr–Al–C systems by self-propagating high-temperature synthesis

In this paper, phase composition of the Mn＋l- AXn phases by self-propagating high-temperature synthesis （SHS） was determined using Ti, Cr, A1, and carbon black as raw materials. And, phase composition and micro- structures of the Mn＋1AXn phases-contained bulk by SHS with the pseudo-hot isostatic pressing （SHS/PHIP） were investigated in Ti-Cr-AI-C systems raw materials. Riet- veld XRD refinement was introduced to study the lattice parameters and phase composition of the resultant phases from the SHSed and SHS/PHIPed samples. Ti2A1Cx, Ti3A1C2, and Cr2A1Cx by SHS were detected in the Ti-Cr- A1-C systems, as well as the binary carbide of TiC and intermetallics. The mechanical properties of the synthe- sized bulk samples were determined, exhibiting a high strength and toughness compared with the typical mono- lithic Mn＋1AXn phase 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＋1AXn phase.