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

Abstract

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.