CN-117966076-B - Gadolinium-enriched nickel-based alloy processing performance improving method and modified gadolinium-enriched nickel-based alloy

Abstract

The invention discloses a gadolinium-enriched nickel-based alloy processing performance improving method. The gadolinium-enriched nickel-base alloy comprises an austenite base body and a second-phase compound Ni 5 Gd distributed among dendrites of the austenite base body, wherein the processing performance of the gadolinium-enriched nickel-base alloy is improved by carrying out oxidation treatment on the gadolinium-enriched nickel-base alloy so that part of the second-phase compound Ni 5 Gd is converted into gadolinium oxide. The invention also discloses a modified gadolinium-enriched nickel-based alloy. Compared with the prior art, the gadolinium-enriched nickel-based alloy is modified by a simple and easy oxidation process, so that part of the second-phase compound Ni 5 Gd is converted into finer gadolinium oxide, thereby effectively inhibiting the generation of processing cracks and greatly improving the breaking elongation of the material, and providing a low-cost effective way for the industrial application of the gadolinium-enriched nickel-based alloy.

Inventors

• JIANG LI
• FU XIN
• LI ZHIJUN

Assignees

• 中国科学院上海应用物理研究所

Dates

Publication Date

20260508

Application Date

20240130

Claims (5)

1. 1. A method for improving the processability of gadolinium-enriched nickel-base alloy comprises an austenite base body and a second phase compound Ni 5 Gd distributed among dendrites of the austenite base body, and is characterized in that the gadolinium-enriched nickel-base alloy is subjected to oxidation treatment so that part of the second phase compound Ni 5 Gd is converted into gadolinium oxide.
2. 2. The method for improving the workability of a gadolinium-enriched nickel-base alloy according to claim 1, wherein the oxidation treatment is performed by exposing the gadolinium-enriched nickel-base alloy to be treated to an atmosphere having an oxygen content of not more than a threshold oxygen content, the oxygen content being such that the oxygen content is just as high as required to convert all of the second phase compound Ni 5 Gd in the gadolinium-enriched nickel-base alloy to gadolinium oxide, and maintaining the temperature below 1260 ℃.
3. 3. The gadolinium-enriched nickel-base alloy processability improving method according to claim 2, wherein the heat is preserved at a temperature of 1000 ℃ to 1250 ℃.
4. 4. The method for improving the processability of a gadolinium-enriched nickel-base alloy according to claim 1, wherein the gadolinium-enriched nickel-base alloy has an oxidation depth of 100 μm to 500 μm along the distribution direction of Ni 5 Gd after the oxidation treatment.
5. 5. A modified gadolinium-rich nickel-base alloy, characterized in that the gadolinium-rich nickel-base alloy is treated by the gadolinium-rich nickel-base alloy machinability improving method according to any one of claims 1-4, and a part of the second phase compound Ni 5 Gd in the gadolinium-rich nickel-base alloy is converted into gadolinium oxide.

Description

Gadolinium-enriched nickel-based alloy processing performance improving method and modified gadolinium-enriched nickel-based alloy Technical Field The invention relates to an alloy modification method, in particular to a gadolinium-enriched nickel-based alloy processing performance improvement method. Background Along with the rapid development of world economy, how to efficiently solve the energy demand, reduce the emission of greenhouse gases, alleviate the atmospheric pollution and the like has important significance. Nuclear energy is a clean, efficient and stable energy source, and has become a strategic focus for long-term planning of energy sources in various countries. The continuous accumulation of spent fuel may become one of key elements for restricting the sustainable development of nuclear power. The closed cycle of spent fuel requires post-treatment of the spent fuel to recover the available elements therein. This inevitably increases the flow of spent fuel handling, transportation, handling and storage. In view of the specific properties of spent fuel, it is important to avoid reaching subcritical conditions during transportation or storage of spent fuel. Neutron absorbing material is a key material for manufacturing spent fuel storage and transportation baskets and partition plates. Current spent fuel containers typically have a 12-38 cm thick housing comprised of steel and concrete. With this material and thickness, the full load weight is about 150 tons, but only 20 tons of spent fuel can be carried. Therefore, the development of the structural and functional integrated material is quickened, and the method is particularly important for the weight reduction of the spent fuel storage and transportation container. At present, main neutron absorbing materials are concrete materials, high polymer composite materials, B 4 C/Al-based composite materials, boron-containing stainless steel and the like. The concrete material is one of the spent fuel storage and transportation barrels which are used at the earliest time, has good development, relatively low price and good shielding effect, but is very inconvenient to transport due to large volume and heavy weight, greatly limits the prospect of the concrete material, lead-boron polyethylene consists of B 4 C, lead and polyethylene, but has poor mechanical property and ageing resistance, cannot be fire-resistant and limits the application to a certain extent, the B 4 C/Al-based composite material is a research hot spot, researchers prepare Al-B 4 C metal by adopting a stirring casting technology, has poor tensile strength and elongation rate, can easily generate harmful second phases, such as Al 3BC、Al4C3、AlB2 and AlB 12C2, and boron-containing austenitic stainless steel has excellent thermal neutron attenuation capability, but the reaction of neutrons and B can generate, which leads to irradiation expansion and deterioration of mechanical property. Non-metallic fillers and non-metallic substrates and non-metallic fillers and metallic substrates are not ideal due to the large differences in physical and mechanical properties. The gadolinium element has a larger equivalent thermal neutron absorption section which is tens of times that of the boron element, so that the gadolinium element has stable thermal neutron radiation and better thermal stability, and the gadolinium element has recently received attention from students at home and abroad. Robino et al studied the corrosion resistance and mechanical properties of gadolinium-enriched 304L alloys of 316 stainless steel with different gadolinium contents, ha and Kim et al. However, since gadolinium is also insoluble in iron-based austenite such as 304 stainless steel and 316 stainless steel, and is formed of low melting point compound (Fe, cr, ni) 3 Gd, its melting point is around 1060 ℃, the solidification temperature range is widened, the hot working window is lowered, which results in difficult working of the material, and solidification cracks are easily generated during welding, so that it is difficult to make a large-sized member satisfying thermal neutron absorption. In order to solve the problem of the low melting point second phase, researchers have proposed adding gadolinium element to nickel-based superalloys to obtain gadolinium-enriched nickel-based alloys, for example, various gadolinium-enriched nickel-based alloys based on Ni-Mo-Cr have been developed by national laboratory complex Lehigh University in Eda state in 2005, and Ni-Cr-Fe and Ni-Cr-W-based gadolinium-enriched nickel-based alloys and Ni-Cr-Mo-Fe-based gadolinium-enriched iron-based nickel-based alloys materials with different gadolinium contents have been developed by Shanghai university in 2022. In these gadolinium-rich nickel-base alloys, gd is also insoluble in the base, but is present as a high melting point compound Ni 5 Gd distributed along the austenite base dendrites with a eutectic temperature point around 1260 ℃,