HRXRD study of the theoretical densities of novel reactive sintered boride candidate neutron shielding materials

https://doi.org/10.1016/j.nme.2020.100732Get rights and content
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Highlights

  • Novel Reactive Sintered Borides (RSBs) are candidate radiation shielding materials.

  • RSBs were prepared by sintering boron carbide, iron-chrome alloy and tungsten metal.

  • Phase abundance and theoretical density ρXRD determined by X-ray diffraction (XRD).

  • Sintered RSBs converged towards atomic compositions W: Fe: B = 1: 1: 1.

  • Highest relative density (ρ/ρXRD) = 99.3% for RSB composition W: Fe: B ≈ 1: 1:1.

Abstract

Reactive Sintered Borides (RSBs) are novel borocarbide materials derived from FeCr-based cemented tungsten (FeCr-cWCs) show considerable promise as compact radiation armour for proposed spherical tokamak (Humphry-Baker, 2007 [1], [2], [3], [4], [5]. Six candidate compositions (four RSBs, two cWCs) were evaluated by high-resolution X-ray diffraction (XRD), inductively coupled plasma (ICP), energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM) to determine the atomic composition, phase presence, and theoretical density.

RSB compositions were evaluated with initial boron contents equivalent to 25 at%<x < 40 at%. Stable RSB bodies formed from sintering for compositions where B at%>30 at%. All RSB compositions showed delamination and carbon enrichment in the bulk relative to the surface, consistent with non-optimal binder removal and insufficient sintering time. Phase abundance within RSBs derived from powder XRD was dominated by iron tungsten borides (FeWB/FeW2B2), tungsten borides (W2B5/WB) and iron borides. The most optimal RSB composition (B5T522W) with respect to physical properties and highest ρ/ρtheo had ρtheo = 12.59 ± 0.01 g cm−3 for ρ/ρtheo = 99.3% and had the weigh-in and post-sintered W: B: Fe abundance closest to 1: 1: 1. This work indicates that despite their novelty, RSB materials can be optimized and in principle be processed using existing cWC processing routes.

Keywords

Radiation shielding
Nuclear fusion
Tungsten borides
Cemented carbides
XRD
Powder metallurgy

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