Research On Structure And Performance Of A Zr-based Nuclear Composite Material

Nuclear power is a clean energy source, which has been developped rapidly in China since thebeginning of21th Century. The service life of a nuclear power plant is an important indicator of therunning capability, the economic and social value, as well as its safety. The so-called nuclear materialsusually are the structural materials or function materials employing in the nuclear power plant, whoseresistance of the particle radiation (such as the neutron) during the process of nuclear fission and evennuclear fusion strongly affect its service life. So far, various crystalline alloys (such as Zr-, Fe-andNi-based alloys) are largly used as the structural materials or function materials in the reactor of anuclear power plant, because of their excellent mechanical properties. However, after a long servicetime, their mechanical properties deteriorate rapidly with the particle radiation (the so-called radiationdamage), because their structures are changed at the micro-and meso-scales that a partialcrystal-nanocystal/amorphous transition occurs. So far, various methods have been developed toenhance the radiation resistance of these alloys, including: micro-alloying, plating ceramic on theirsurface and annealing treatment. However, there are some disadvantages in these methods. Thus, it isrequired to develop new type of alloys to serve as nuclea materials. In this paper, the Zr-basedcomposite alloys were prepared by depositing an amorphous film on the pure Zr plate. Then thestructure and properties of the Zr-based composites were measured.A series of the ternary Zr-based amorphous thin films were prepared by adding a third elementsuch as Nb or Ni in the ZrCu binary system, using the magnetron co-sputtering method. And then thestructure was charactered and analysed using X-ray diffraction and high resolution transmissionelectron microscope. It is found that although there are a few of nanocrystalline particles in the filmsmicrostructure by changing Nb or Ni concentrations in the Zr-based amorphous alloy, such ternaryfilms exhibit the long-range disordered amorphous structure. With the increase of Ni or Nb, theamorphous diffraction peak shifts to different direction, and the peak intensity also increases.The Zr-based composites were prepared by depositing ternary amorphous film on the purezirconium surface via the magnetron sputtering. The Zr plate coated with Zr53Cu38Nb9amorphouslayer was selected as a typical material to be tested its anti-corrosion and mechanical properties. Itwas found that the corrosion resistance of this composite material is better than the pure zirconium,and it was also observed that the composites exhibit better corrosion resistance with the increase ofNb composition. It is revealed that the bending resistance and the tensile strength of the compositescan be significantly enhanced. In particular, such composite material has the best tensile ductilitywhen its amorphous film has a thickness of457nm. Doping the third element in the ZrCu alloy system can increase its glass-forming ability (GFA)and physical and chemical properties, because of the ZrCu alloy microstructure is affected by minoraddition. Thus, a representative Zr48Cu45Al7amorphous alloy and a corresponding Zr50Cu50binaryalloy were selected as the research prototypes, and their microstructure was investigated bysynchrotron radiation experiments. It is revealed that the doped Al atoms have strong interactions withtheir neighbor atoms, leading to the bond shortening and volume shrinkage of cluster.The factorscontribute to the atomic-and cluster-level dense packing in the local structures.Such dense packingshould be the structural origin of the high GFA and physical and chemical properties caused byAl-microalloying in the ZrCu system.