Tuesday  |  Virtual Track 1  |  09:24 AM–09:36 AM

#11796, Effect of Grain Orientation on the Dynamic Compressive Response of Highly-Orientated MAX Phases

MAX phases are 3D nano-laminar solids comprising of early transition metals (M), A group elements (A), and carbide and nitride (X). They have plate-like grains with unit structures of M4AX3, M3AX2 and M2AX. These solids bridge the gap between metals and ceramics with potentially desirable strength and toughness combinations. As such, MAX phases could be used as replacement materials for high efficiency engine and nuclear cladding components, to name a few, which requires resistance to not only quasi-static, but dynamic loading events. Texturing ceramics, including MAX phases, have shown improved mechanical properties compared to their random-oriented variants and could introduce the ability to specifically tailor microstructures to various applications. Consequently, this study examines the effect of global grain orientation on the compressive behavior of MAX phases, focusing on highly oriented Ta4AlC3, Ti3SiC2 and Ta2AlC polycrystalline sample fabricated by a hot forging technique. X-ray diffraction is used to verify the grain orientation and scanning electron microscopy is utilized to characterize the microstructure and obtain the pre-and-post-mortem fractography. Kolsky (Split-Hopkinson) bars are used to study the high strain-rate compressive response with respect to the textured direction and the results are compared with quasi-static compressive results. Digital image correlation (DIC) technique is used to map full-field kinematics up until fracture during loading and the results are compared with traditional strain-gauge global stress-strain results. The compressive response of highly-oriented Ti3SiC2 exhibits a peak compressive strength of 782 MPa when loading perpendicular to the c-axis under quasi static conditions, increasing to 984 MPa under dynamic loading. However, when loading parallel to the c-axis, the compressive stress was far less sensitive to the strain rate. Further compressive experiments will be conducted on Ta4AlC3 and Ta2AlC and the influence of grain orientation on the anisotropic dynamic compression response under two orientations and varied strain rates, and the associated failure mechanics will be discussed.

Xingyuan Zhao   Colorado School of Mines
Maxim Sokol   Tel-Aviv University
Tarek Elmelegy   Drexel University
Michel Barsoum   Drexel University
Leslie Lamberson   Colorado School of Mines