Influence of ball milling processing on the microstructure and characteristic of W–Nb alloy

Mechanical alloying was performed in a planetary ball mill by using a rotational speed of 400 r/min and a ball to powder ratio of 20:1 at room temperature. Milling was performed for 5, 15, 25, 36, and 45 h. The effect of milling time on the microstructure and properties of alloy powders, microstructure of W-Nb alloys, and second-phase distribution were studied through field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray diffraction analyses. Results showed that crystalline size, lattice strain, and dislocation density significantly changed when the milling time was increased from 5 h to 25 h. Further increase in the milling time slightly influenced the parameters. W-Nb alloy powders exhibited the lowest lattice parameters after 25 h of milling. Among the formed W-Nb solid solutions, W-Nb alloy milled for 25 h exhibited the lowest porosity and contained homogenously and finely distributed Nb-rich phases in the tungsten grains and boundaries. Thermal desorption spectroscopy analysis was also performed to assess deuterium retention after irradiation. Based on the total amount of deuterium in the W-Nb alloys, those milled for 25 h exhibited the optimal irradiation resistance. In conclusion, 25 h is the optimal milling time for mechanical manufacture of W-Nb alloys. (C) 2016 Elsevier B.V. All rights reserved.