Fe-Base Alloy Powder for Neutron Absorption
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Solution Overview
Problem
Boron-containing stainless steels used in the nuclear industry face challenges with reduced corrosion resistance, ductility, and impact toughness due to boron additions, and the high cost of enriched B10 limits their practical application, while conventional processing issues such as cracking and tearing restrict boron content.
Innovation Solution
A corrosion-resistant, austenitic alloy with a composition that includes boron and gadolinium, processed through powder metallurgy to form boride and gadolinide particles, enhancing strength, toughness, and processability while maintaining corrosion resistance and neutron absorption capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If boron is added to stainless steel to increase thermal neutron absorption, then neutron absorption capability is improved, but corrosion resistance deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by adding gadolinium (0.01-5.0 wt%) alongside controlled boron (0.01-3.0 wt%) to modify the alloy's neutron absorption mechanism while preserving corrosion resistance through optimized Cr (18-30 wt%) and Ni (8-20 wt%) content
Solution Approach 2:
The patent creates a composite alloy system combining stainless steel base material with boron and gadolinium additives, forming a multi-element composite that leverages the high neutron absorption of both boron and gadolinium while maintaining the corrosion resistance of the stainless steel matrix
2Reliability
If boron content is increased to enhance neutron absorption, then thermal neutron absorption capability is improved, but mechanical properties (ductility and toughness) deteriorate
Solution Approach 1:
The patent optimizes the boron content parameter to a controlled range (0.01-3.0 wt%) and introduces gadolinium (0.01-5.0 wt%) to achieve the desired neutron absorption with reduced boron, thereby minimizing the formation of brittle borides and preserving mechanical properties
Solution Approach 2:
The patent extracts some of the neutron absorption function from boron alone and transfers part of it to gadolinium, reducing the total boron content needed and consequently reducing the harmful effects of boron on ductility and toughness
3Ease of manufacture
If conventional processing methods are used for boron-containing stainless steel, then manufacturing is simplified, but processing issues (cracking and tearing) occur
Solution Approach 1:
The patent modifies the chemical composition parameters (adding gadolinium, optimizing Cr and Ni content) to fundamentally change the material's processing behavior, enabling conventional hot working methods to succeed where they previously failed due to cracking and tearing
4Reliability
If enriched B10 is used to maximize neutron absorption, then thermal neutron absorption capability is improved, but cost increases
Solution Approach 1:
The patent substitutes expensive enriched B10 boron with cheaper natural boron combined with gadolinium, creating a cost-effective alternative that achieves equivalent or superior neutron absorption performance through the synergistic effect of multiple neutron-absorbing elements
Solution Approach 2:
The patent creates a composite neutron absorption system using natural boron and gadolinium together, where gadolinium's high thermal neutron absorption cross-section compensates for using non-enriched boron, significantly reducing material costs while maintaining performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The alloy achieves a novel combination of strength, toughness, and corrosion resistance, allowing for higher boron equivalency without the processing issues of conventional methods, and reduces the need for expensive enriched B10 by using gadolinium as a more potent neutron absorber.
Implementation Method 1
the benefit provided by boron to the nuclear power industry is related to its effect of increasing a material's thermal neutron absorption cross-section
Data Source
AI summary
A corrosion resistant, neutron absorbing, austenitic alloy powder is disclosed having the following composition in weight percent.C0.08 max.Mnup to 3Siup to 2P0.05 max.S0.03 max.Cr17-27Ni11-20Mo + (W/1.92) up to 5.2BEq0.78-13.0O 0.1 max.N up to 0.2Yless than 0.005The alloy contains at least about 0.25% B, at least about 0.05% Gd, and the balance of the alloy composition is iron and usual impurities. BEq is defined as % B+4.35×(% Gd). An article of manufacture made from consolidated alloy powder is also disclosed which is characterized by a plurality of boride and gadolinide particles dispersed within a matrix. The boride and gadolinide particles are predominantly M2B, M3B2, M3X, and M5X in form, where X is gadolinium or a combination of gadolinium and boron and M is one or more of the elements silicon, chromium, nickel, molybdenum, iron.