Abstract
The room temperature yield end fracture stresses have been measured for a series of high-purity polycrystalline molybdenum tensile specimens with grain diameters varying from 0.03 mm to 0.26 mm. The yield stress results can be fitted to Petch's relation [sgrave]Y =[sgrave]I+kYl−1/2 with [sgrave]I= = 11.00 kg mm−l and kY= 1.7 × 102 dyne cm−22/2. The fracture stress curve tends to a constants height above the yield stress curve as the grain ah decreases. Using a theory of fracture recently proposed by Cottrell the effective surface energy for fracture in estimated to be 12 000 ergs cm−2.

This publication has 0 references indexed in Scilit: