Silicon nitride

Linguistics

Phase (matter)

Philosophy

Slip (aerodynamics)

Metallurgy

Materials science

Stress (linguistics)

Ceramic

Layer (electronics)

Silicon

Thermodynamics

Physics

Organic chemistry

Chemical bond

Composite material

Chemistry

Brittleness

Covalent bond

Nitride

Science

Covalently bonded ceramics exhibit preeminent properties-including hardness, strength, chemical inertness, and resistance against heat and corrosion-yet their wider application is challenging because of their room-temperature brittleness. In contrast to the atoms in metals that can slide along slip planes to accommodate strains, the atoms in covalently bonded ceramics require bond breaking because of the strong and directional characteristics of covalent bonds. This eventually leads to catastrophic failure on loading. We present an approach for designing deformable covalently bonded silicon nitride (Si3N4) ceramics that feature a dual-phase structure with coherent interfaces. Successive bond switching is realized at the coherent interfaces, which facilitates a stress-induced phase transformation and, eventually, generates plastic deformability.

Plastic deformation in silicon nitride ceramics via bond switching at coherent interfaces