Element W can effectively improve the density of energetic structural materials. However, W is an inert element and does not combust in air. To change the reaction characteristics of W, 60 at.% Al was introduced into ...Element W can effectively improve the density of energetic structural materials. However, W is an inert element and does not combust in air. To change the reaction characteristics of W, 60 at.% Al was introduced into W through mechanical alloying. XRD analysis shows that after 50 h of ball milling, the diffraction peak of Al completely disappears and W(Al60) super-saturated solid solution powder is obtained. Further observation by HAADF and HRTEM reveals that the W(Al60) super-saturated solid solution powder is a mixture of solid solution and amorphous phase. Based on the good thermal stability of W(Al60) alloy powder below 1000℃, W(Al60)-Al composite was synthesized by hot pressing process.Impact initiation experiments suggest that the W(Al60)-Al composite has excellent reaction characteristics, and multiple types of tungsten oxides are detected in the reaction products, showing that the modified W is combustible in air. Due to the combustion of tungsten, the energy release rate of the W(Al60)-Al composite at speed of 1362 m/s reaches 2.71 kJ/g.展开更多
The characteristics of morphologies and changes of the microstructures in mechanically alloyed （MA） （m（Cr）∶m（C）∶m（Cr）=90∶1∶9） mixed powders were investigated by using SEM observation and X-ray diffracti...The characteristics of morphologies and changes of the microstructures in mechanically alloyed （MA） （m（Cr）∶m（C）∶m（Cr）=90∶1∶9） mixed powders were investigated by using SEM observation and X-ray diffraction （XRD） analyses. The results show that Cu, C and Cr mixed powders mechanically alloyed for 12 h forms the Cu-based super-saturated solid solution; after high energy ball-milling for 96 h the partial solute elements Cr and C precipitate, meanwhile, the mechanochemical reactions take place and the carbides Cr7C3 form. The composite powders after mechanically alloyed are fine and flat. The formed defects such as free surface, grain boundary, sub-grain boundary and dislocation decrease diffusion activity energy, which is the important reason for developing super-saturated solid solution and promoting the second phase precipitation.展开更多
Mechanical alloying was employed to produce super—saturated solution of Fe_1-xCu_x ,which is virtually immiscible under an equilibrium condition at ambient temperature.XRD results show that the solutions formed in th...Mechanical alloying was employed to produce super—saturated solution of Fe_1-xCu_x ,which is virtually immiscible under an equilibrium condition at ambient temperature.XRD results show that the solutions formed in the concentration ranges of x≤O.15 and x≥0.40 are of bee structure of x-Fe and fee structure of Cu,respectively.For the region in between (0.15<x<0.40),however,the alloy obtained is a mixture of bee plus fee phases.DSC traces indicate that there exist two broad exothermal peaks for all samples,the first peak responds to the releasing of stored strain and the second to the decomposition of solid solutions.展开更多
基金supported by the National Natural Science Foundation of China, [Award number: 11972372] and [Award number: U20A20231]。
文摘Element W can effectively improve the density of energetic structural materials. However, W is an inert element and does not combust in air. To change the reaction characteristics of W, 60 at.% Al was introduced into W through mechanical alloying. XRD analysis shows that after 50 h of ball milling, the diffraction peak of Al completely disappears and W(Al60) super-saturated solid solution powder is obtained. Further observation by HAADF and HRTEM reveals that the W(Al60) super-saturated solid solution powder is a mixture of solid solution and amorphous phase. Based on the good thermal stability of W(Al60) alloy powder below 1000℃, W(Al60)-Al composite was synthesized by hot pressing process.Impact initiation experiments suggest that the W(Al60)-Al composite has excellent reaction characteristics, and multiple types of tungsten oxides are detected in the reaction products, showing that the modified W is combustible in air. Due to the combustion of tungsten, the energy release rate of the W(Al60)-Al composite at speed of 1362 m/s reaches 2.71 kJ/g.
文摘The characteristics of morphologies and changes of the microstructures in mechanically alloyed （MA） （m（Cr）∶m（C）∶m（Cr）=90∶1∶9） mixed powders were investigated by using SEM observation and X-ray diffraction （XRD） analyses. The results show that Cu, C and Cr mixed powders mechanically alloyed for 12 h forms the Cu-based super-saturated solid solution; after high energy ball-milling for 96 h the partial solute elements Cr and C precipitate, meanwhile, the mechanochemical reactions take place and the carbides Cr7C3 form. The composite powders after mechanically alloyed are fine and flat. The formed defects such as free surface, grain boundary, sub-grain boundary and dislocation decrease diffusion activity energy, which is the important reason for developing super-saturated solid solution and promoting the second phase precipitation.
文摘Mechanical alloying was employed to produce super—saturated solution of Fe_1-xCu_x ,which is virtually immiscible under an equilibrium condition at ambient temperature.XRD results show that the solutions formed in the concentration ranges of x≤O.15 and x≥0.40 are of bee structure of x-Fe and fee structure of Cu,respectively.For the region in between (0.15<x<0.40),however,the alloy obtained is a mixture of bee plus fee phases.DSC traces indicate that there exist two broad exothermal peaks for all samples,the first peak responds to the releasing of stored strain and the second to the decomposition of solid solutions.
