Metal matrix nanocomposites (MMNCs) are those metal matrix composites where the reinforcement is of nanometer dimensions, typically less than 100 nm in size. Also, it is possible to have both the matrix and reinforcement phases of nanometer dimensions. The improvement in mechanical properties of MMNCs is attributed to the size and strength of the reinforcement as well as to the fine grain size of the matrix. Spark plasma sintering has been used extensively over the past years to consolidate wide range of materials including nanocomposites and was shown to be effective noneconventional sintering method for obtaining fully dense materials with preserved nanostructure features. The objective of this work is to briefly present the spark plasma sintering process and review published work on spark-plasma-sintered metals and metal matrix nanocomposites.

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Molecular dynamic crystals conveniently combine flexibility required for mechanical reconfiguration, strength for effective translation of elastic energy, and long-range order of mechanically coupled molecules for rapid conversion of disordered motion (heat) or photons (light) into ordered motion (work). By direct measurement of the actuation force generated by crystals of a thermosalient solid, here we describe the first direct quantification of the work performed and energy conversion that can be accomplished by using dynamic crystals as supramolecular actuators. Upon reversible α-to-γ phase transition, crystals of (phenylazophenyl)palladium hexafluoroacetylacetonate of submillimeter to millimeter size exert forces in the range of 1–100 mN upon longitudinal and lateral expansion. This work translates to a volumetric power density of about 1–3 MW m–3 and efficiency comparable to the existing multicomponent actuators.

Silver-coated 1,2,4,5-tetrabromobenzene crystals, a thermosalient compound, are presented as novel electrical fuse materials. These electrically conductive crystals exhibit linear characteristics up to a threshold value where the resistive heating triggers their phase transformation. This causes mechanical motion of the crystals with immediate circuit breakage. The concept described here opens new avenues for next-generation electrical fuses.