Nanomechanics of Refractory Transition‐Metal Carbides: A Path to Discovering Plasticity in Hard Ceramics

Abstract

Refractory carbides of transition metals (Zr, Ta, etc.), owing to a mixture of ionic, covalent, and metallic bonding, exhibit high hardness (10s of GPa), high elastic moduli (100s of GPa), good resistance to wear, ablation, and corrosion, high‐temperature mechanical strength, along with good electrical conductivities. They are attractive as high‐temperature structural components in aerospace vehicles. Although these materials are exceptionally hard, their structural applications at low temperatures have been limited because of their brittleness. The design of ceramic materials possessing both high hardness and enhanced ductility has been a long‐standing challenge. Various research studies have focused on this topic with limited success. Here, we present a brief review of our recent results obtained from direct observations of mechanical deformation during uniaxial compression of group IV and group V transition‐metal carbide (ZrC and TaC) single crystals inside a transmission electron microscope. Our studies provide new insights into the mechanical deformation mechanisms and help to identify strategies for enhancing room‐temperature plasticity in this class of materials.

Shear‐induced brittle failure of titanium carbide from quantum mechanics simulations

“…Ceramics are generally regarded to possess high hardness and low ductility compared with metals because of their predominantly covalent or/and ionic bonding . Developing materials that have metal‐like ductility and high hardness as ceramics is of great interest for a wide range of engineering applications such as piston head, cutting tools, and rocker arms in automobile engines .…”

“…Ceramics are generally regarded to possess high hardness and low ductility compared with metals because of their predominantly covalent or/and ionic bonding. 1 Developing materials that have metal-like ductility and high hardness as ceramics is of great interest for a wide range of engineering applications such as piston head, cutting tools, and rocker arms in automobile engines. 2,3 Transition-metal carbides are one of promising candidate materials due to their superior mechanical, physical, and chemical properties such as high wear resistance, high hardness, good chemical resistance, and low friction coefficients.…”

Deformation behavior of nanocrystalline titania particles accessed by complementary in situ electron microscopy techniques

“…Grain rotations, grain shifts and grain boundary sliding were observed as a function of grain size, indicating that smaller grains promote the deformation by the above-mentioned mechanisms. 10,[21][22][23][24] To avoid any structural changes during sample preparation and handling, well defined metal oxide particles from different synthesis routes can be used. However, for all these studies sample preparation artifacts due to focused ion beam (FIB) machining or conventional ion polishing cannot be ruled out: ions (typically Ar + or Ga + ) from the beam used for machining might influence the existing defect structures prior to compression and might thus influence the mechanical behavior.…”

Microcompression of brittle and anisotropic crystals: recent advances and current challenges in studying plasticity in hard materials

“…[2,[21][22][23][24][25][26][27][28][29][30][31][32] A selection of materials thus studied in terms of their plasticity is shown in Fig. 2, while Figs.…”

“…Among the systems, which have been studied to date by research groups around the globe are Cu-Sn phases (solders), carbides and nitrides, MAX phases, binary nickel and iron aluminides, metallic and silicate glasses, high entropy alloys and quasicrystals, [2,[21][22][23][24][25][26][27][28][29][30][31][32]36,[44][45][46][47][48] see also Fig. 2.…”