The Strengthening of Hexagonal Close-Packed Materials Due to the Presence of Grain Boundaries.

摘要

The grain size,temperature and strain rate dependences of the stress-strain behavior of polycrystalline hcp metals are analyzed on the basis of a combined Hall-Petch and thermal activation strain rate analyses. The polycrystal parameters are related to single crystal resolved stresses and it is shown that the temperature dependence of Hall-Petch slope k sub epsilon is responsible for the grain size dependence of the strain rate sensitivity and ductile-brittle transition. The flow and fracture behavior of polycrystalline zinc and titanium at 4.2K provided an interesting comparison of the near-brittle failure of zinc as compared with the near-ductile fracture of titanium.