Field-assisted sintering technology (FAST), as a fast densification method with low process temperature, was used to manufacture self-passivating tungsten alloys (SPTAs) of W-Cr-Zr in this work. To clarify the behaviors of grain growth and Cr-rich phase precipitation under the action of electric current during the densification process, interrupted sintering at different temperatures (600–1000 °C) were performed. According to the viscous flow theory, the activation energy of W-Cr-Zr sample for densification is ~23 kJ/mol. The differential form of power law was adopted to evaluate the grain growth behavior. It is found that the W-Cr-Zr alloy consolidated by FAST has a low activation energy for grain growth of 82 kJ/mol. The Cr-rich phase could be confirmed by XRD spectra even when the sintering was interrupted at 600 °C. From the characterization of the cross-sectional microstructure, the Cr-rich phases tend to precipitate at sintering necks and defects (cracks/voids) in particle interiors. The low formation temperature of the Cr-rich phase is attributed to local overheating caused by local high electric current. This work provides significant insight into the mechanisms underlying the densification and the evolution of the microstructure of the SPTAs during the FAST process.

在这项工作中，现场辅助烧结技术（FAST）作为一种低工艺温度的快速致密化方法，被用于制造W-Cr-Zr的自钝化钨合金（SPTA）。为了阐明在致密化过程中电流作用下晶粒的生长和富铬相的析出行为，在不同温度（600–1000°C）下进行了间断烧结。根据粘性流动理论，W-Cr-Zr样品致密化的活化能为〜23 kJ / mol。幂律的微分形式被用来评估晶粒的生长行为。发现通过FAST固结的W-Cr-Zr合金对于晶粒生长具有82kJ / mol的低活化能。即使在600°C下中断烧结，也可以通过XRD光谱确认富铬相。从横截面微观结构的表征来看，富铬相倾向于在烧结颈处沉淀，并在颗粒内部形成缺陷（裂纹/空隙）。富Cr相的低形成温度归因于局部高电流引起的局部过热。这项工作提供了重要的见解，在FAST过程中SPTA的致密化和微观结构演变的潜在机制。