Properties of nanocrystalline zinc produced by gas condensation

Abstract

The design and operation of an experimental facility to generate nanocrystalline zinc by the expansion of zinc and argon vapor in a supersonic free jet are described. The grain size of the compacted nanocrystalline zinc was found to lie between 10 and 20 nm and could be controlled by the zinc mole fraction in the stream and the back pressure in the expansion section. Measurements of physical properties show that nanocrystalline zinc is 5 to 7 times harder than polycrystalline material and the hardness decreases with increasing grain size. Some results from strain rate sensitivity and positron annihilation experiments are also reported. © 1994.