Study Of Valence Electron Structure And Microstructure And Properties Of W-Mo Solid Solution

Based on the empirical electron theory of solids and molecules (EET)、the bond length difference method (BLD) and the average atom model, the valence electron structure of W-Mo solid solution was analyzed, the electron density of the strongest bond (nA)、intensity factor (η) and the bond energy (Ea) of W-Mo solid solution with different Mo content were calculated, and the relationship between valence electron structure parameters and mechanical properties of W-Mo alloy was studied. Subsequently, W-Mo alloys with different Mo content were fabricated by Mechanical Alloy and Spark Plasma Sintering (SPS) as well as atmosphere sintering. The phase and microstructure of W-Mo alloys were investigated by means of X-ray diffractometer (XRD), optical microstructure (OM) and scanning electron microscope (SEM) combination with energy dispersive spectrometer (EDS), the relative density and hardess were measured. The effects of Mo content and different sintering methods on microstructure and properties of W-Mo alloys were studied.The effect of different Mo content on he valence electron structure of W-Mo solid solution was studied, and the relationship between valence electron structure parameters (nA、η) with hardness and strength of W-Mo solid solution was analzed. Studies show that with the increase of Mo content within a certain range, the covalence electron number (nA) on the strongest bond and the intensity factor (η) of W-Mo solid solution all increase gradually, indicating the increase of hardness and strength of W-Mo solid solution. When the Mo content is about 45 wt%, nA and η of W-Mo solid solution reach its maximum,indicating the hardness and the strength of W-Mo solid solution also reach its maximum.W-Mo alloy powders with different Mo content were fabricated by Mechanical Alloy On the basis of the theoretical calculation. The effect of Mechanical alloying process parameters (proces control agent、 milling time) on the grain size and morphology of W-Mo alloy powder was studied. The best Mechanical alloying process of the fabrication of W-Mo alloy powder has been determined:the milling time is 36h, the content of proces control agent is 5 wt%, the weight ratio of ball-to-powder is 15:1, the rotation speed of milling is 300r/min.The single-phase W-Mo solid solution is formed after SPS (1800℃) as well as atmosphere sintering (2000℃). The diffraction peak of W-Mo alloy deviates to the high angle gradually with Mo content increases, indicating that the addiction of Mo can refine the grain and shorten the interplanar spacing of W-Mo alloy. The relative density of W-Mo alloy increases and the grain size become smaller with the increase of Mo content within a certain range. The hardness of W-Mo alloy also increases with the increase of Mo content. The hardness of W-Mo alloy reaches its maximum while the Mo content is about 45 wt%. Because of special sintering mechanism and rapid sintering time, W-Mo alloys fabricated by SPS sintering have smaller grain size, higher relative density and higher hardness than that fabricated by atmosphere sintering. W-45Mo alloy fabricated by SPS sintering has excellent microstructure and property:the grain size is 6-7μm, the relative density reaches 95.8% and the hardness reaches 579.2MPa.