The hardness requirement serves as an important guarantee of surface scratch resistance, wear resistance, and decontamination performance for tungsten alloy shielding containers while reflecting microstructural uniformity and processing quality. Hardness must achieve a relatively high level while ensuring sufficient toughness to withstand repeated mechanical decontamination, accidental impacts, and long-term environmental attack.
To achieve this balance, production controls tungsten powder grain size, binder phase content, and sintering process to form fine, rounded, uniformly distributed tungsten particles creating a continuous skeleton with binder phase fully filling interstices. Matrix hardness must remain consistent throughout the volume, preventing localized soft zones from becoming initiation sites for corrosion or contamination. Surface hardness is further enhanced through boronizing, ion nitriding, or diamond-like carbon coating to form a hard-outer/tough-inner gradient structure.
Hardness uniformity requires all exposed surfaces (including inner cavity, sealing faces, and hole bottoms) to meet specified levels, with no softening or embrittlement in machined altered layers or heat-affected zones. Practical testing combines Vickers hardness, metallographic analysis, and scratch testing to ensure hardness distribution exhibits no significant variation. Surface hardening layers must achieve metallurgical bonding with the substrate and resist spalling or cracking after prolonged irradiation and decontamination cycles.
Appropriate control of hardness requirements enables tungsten alloy shielding containers to maintain mirror-like condition and high decontamination efficiency over extended periods in nuclear medicine hot cells, isotope production, and industrial irradiation facilities, markedly reducing secondary contamination risk.
