Amorphous alloys have attracted extensive attention due to their unique atomic arrangement and excellent properties. However, the application in practical engineering is seriously limited due to the size, crystallization and other problems. Laser additive manufacturing technology has the characteristics of high heating, cooling rate and point by point melting deposition, which provides a new idea for the preparation of amorphous alloys. Zr 50 Ti 5 Cu 27 Ni 10 Al 8 amorphous alloy was prepared on the surface of pure zirconium substrate by selective laser melting technology. The composition and structure of the samples were characterized. The results show that the samples are mainly composed of amorphous phase, and the crystallization mainly occurs in the superimposed zone of heat affected zone. With the decrease of laser power, the area of crystallization zone and the number of crystallization particles decrease. However, if the laser power is too low, there will be non-fusion defects and cracks, which will seriously affect the forming quality and amorphous rate of amorphous alloy.

Light water reactors (LWR) use zirconium-alloy fuel claddings, the tubes that hold the uranium-dioxide fuel pellets. Zr-alloys have very good neutron transparency, but during a loss of coolant accident or beyond design basis accident (BDBA) they can undergo excessive oxidation in reaction with the surrounding steam environment. Relatively thin oxidation-resistant coatings on Zr-alloy fuel cladding tubes can potentially buy coping time in these off-normal scenarios. In this study, cold spraying, solid-state powder-based materials deposition technology has been developed for deposition of oxidation-resistant Cr coatings on Zr-alloy cladding tubes, and the ensuing microstructure and properties of the coatings have been investigated. The coatings when deposited under optimum conditions have very good hydrothermal corrosion resistance as well as oxidation resistance in air and steam environments at temperatures in excess of 1100 °C, while maintaining excellent adhesion to the substrate. These and other results of this study, including mechanical property evaluations, will be presented.

This investigation was conducted to clarify the effects of process parameters on the formation of the new amorphous coating using Zr-based alloy, which is known as bulk metallic glass forming alloy, by a HVOF (High Velocity Oxygen Fuel) spraying process. Powders used for spraying was prepared by vacuum gas atomization and then crushed by a centrifugal mill. HVOF spraying experiments were carried out using a Tafa JP-5000 spraying gun. DTA (Differential Thermal Analysis) measurements have shown that the amorphous content of the coatings was measured up to about 65% depending on the spraying parameters. The amorphous fraction of the coatings is decreased with increasing the spray distance and the fuel flow rate. Microstructural observations and X-ray diffraction analysis of the spray coated layers reveal that the amorphization behavior during the spraying is attributed to the degree of the solidification of droplets and the oxide (ZrO2) formation in spray coated layers. Therefore, flame temperature and spray distance that can control the carrier gas temperature and undercooling effects of the droplets are the most crucial factors for the evolution of the amorphous phase using this bulk metallic glass forming alloy.