Microstructural characterization of U–7Mo/Al–Si alloy matrix dispersion fuel plates fabricated at 500 °C

The starting microstructure of a dispersion fuel plate will impact the overall performance of the plate during irradiation. To improve the understanding of the as-fabricated microstructures of U–Mo dispersion fuel plates, particularly the interaction layers that can form between the fuel particles and the matrix, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses have been performed on samples from depleted U–7Mo (U–7Mo) dispersion fuel plates with either Al–2wt.% Si(Al–2Si) or AA4043 alloy matrix. It was observed that in the thick interaction layers, U(Al, Si)3 and U6Mo4Al43 were present, and in the thin interaction layers, (U, Mo) (Al, Si)3, U(Al, Si)4, U3Si3Al2, U3Si5, and possibly USi-type phases were observed. The U3Si3Al2 phase contained some Mo. Based on the results of this investigation, the time that a dispersion fuel plate is exposed to a relatively high temperature during fabrication will impact the nature of the interaction layers around the fuel particles. Uniformly thin, Si-rich layers will develop around the U–7Mo particles for shorter exposure times, and thicker, Si-depleted layers will develop for the longer exposure times.

弥散燃料板的初始微观结构会影响其在辐照过程中的整体性能。为了更好地理解U - Mo弥散燃料板制造后的微观结构，特别是燃料颗粒与基体之间可能形成的相互作用层，对贫化U - 7Mo（U - 7Mo）弥散燃料板（其基体为Al - 2wt.% Si（Al - 2Si）或AA4043合金）的样品进行了扫描电子显微镜（SEM）和透射电子显微镜（TEM）分析。观察到在厚的相互作用层中存在U(Al, Si)₃和U₆Mo₄Al₄₃，在薄的相互作用层中观察到(U, Mo)(Al, Si)₃、U(Al, Si)₄、U₃Si₃Al₂、U₃Si₅以及可能的USi型相。U₃Si₃Al₂相含有一些Mo。根据这项研究的结果，弥散燃料板在制造过程中暴露于相对高温的时间会影响燃料颗粒周围相互作用层的性质。在较短的暴露时间下，U - 7Mo颗粒周围会形成均匀薄的富Si层，而在较长的暴露时间下会形成更厚的贫Si层。