铀基非晶复合材料的相分离与凝固序列研究

Phase Separation and Solidification Sequence of Uranium-Based Amorphous Composites

用TEM、SEM等对U_(30.03)Zr_(28.83)Ti_(9.66)Ni_(7.00)Cu_(8.75)Be_(15.73)铀基非晶复合材料的微观结构和成分分布进行了表征,发现该复合材料是α-U相和以Zr、Ti为主的非晶相的双相复合材料,其中两相均以球形析出相的方式构成多层次嵌套结构。复合材料在降温过程中,首先发生以形核-长大机制为主的U、Cu两相的相分离,其他合金元素再根据混合焓择优分布;随后的凝固过程为α-U凝固相变与非晶转变的两步过程,并在非晶为球形析出相的区域形成具有过渡层的特殊结构。这些结果为非晶复合材料的成分设计和热处理工艺的调整提供了新思路。

The microstructure and composition distribution of U_(30.03)Zr_(28.83)Ti_(9.66)Ni_(7.00)Cu_(8.75)Be_(15.73)uraniumbased amorphous composites were characterized using TEM and SEM in this study.The composite is a biphasic composite ofα-U and amorphous phases dominated by zirconium and titanium.Both phases form a multilevel nested structure in the form of spherical precipitated phases.During cooling of the composite material,the phase separation of uranium and copper phases dominated by the nucleation-growth mechanism occurs first,and the other alloying elements are then preferably distributed according to the mixing enthalpy.The subsequent solidification is a two-step process:α-U solidification and amorphous transformation.A special structure with a transition layer is formed in the area where the amorphous phase is the spherical precipitated phase.These results provide new insights for the composition design and heat treatment adjustment of amorphous composite materials.