Malka A. Physical Nature of Creep and Long-term Strength of New Heat-resistant Mg-Al-Ca Alloys

The work is devoted to investigation of the physical nature of creep and long-term strength of new heat-resistant Mg-Al-Ca alloys at temperatures of 150-250 °C to optimize their composition and structure for maximizing the creep resistance. The new durability model of heterogeneous materials subjected to the dislocation creep at temperatures above the ductile-brittle transition temperature has been proposed. In the framework of the model a new interrelated theoretical expressions permitting to determine the activation parameters of steady-state creep strain rate and durability have been obtained. The new method of calculating the generalized parameters has been proposed. The original experimental data are in a good agreement with calculated values. The activation analysis have been used to identify the most probable controlling mechanisms that are responsible for the high creep resistance of the new experimental Mg-Al-Ca alloys in the terms of the creep strain rate of about 10-9 s-1 during 200 hours at 150 °C and 65 MPa.