Investigation of solid solution hardening in molybdenum alloys

Mechanical properties of pure molybdenum like yield strength, hardness and creep strength can be modified by alloying elements. The alteration of properties can be described as a result of different mechanisms like solid solution hardening (SSH), particle as well as grain boundary hardening. The aim of this work is to quantify the solid solution hardening effect of different solutes. Therefore the influences of other strength affecting mechanisms like grain boundary hardening or particle hardening have been excluded. Based on the powder metallurgical manufacturing route different molybdenum alloys with Cr, Re, Ta, Ti or W additions were prepared. Vickers hardness measurements at room temperature and tensile tests at 500 °C were performed to quantify the hardening effect. Additionally the modulus of rigidity was measured by ultrasonic inspection and the dynamical resonance method. Lattice parameters were measured by means of X-ray diffraction experiments. Applying existing theories of solid solution hardening an attempt was made to separate and quantify dielastic and parelastic effects.