Effect of the Strain Rate on the Mechanical Properties of Metalloceramic Molybdenum in the Ductile-Brittle Transition Temperature Range

Metalloceramic molybdenum is tested in the temperature range from -100 to +350 degrees C and the strain rate range from 3.4 x 10(-3) to 4 x 10(3) s(-1). This wide strain rate range, which was used for the first time to study molybdenum, makes it possible to find the laws of changes in its strength and deformation characteristics. It is found that the ductile-brittle transition temperature increases from -90 to +250 degrees C in this strain rate range, the dependences of the lower and upper transition temperatures on the strain rate intersect at epsilon = 10(5.7) s(-1), and the effect of the test temperature on the yield strength weakens with increasing strain rate and disappears at epsilon = 10(5.9) s(-1). The closeness of these two strain rates calculated using two different approximations suggests the presence of a certain limiting critical strain rate beginning from which molybdenum is in a brittle state.