We report a set of compression test experiments carried out on sintered uranium dioxide at 1500 $°$C, at constant strain rates and under controlled oxygen partial pressures. The macroscopic data indicate an initial strain hardening stage followed by a quasi steady-state period during which changes in the stress level are sluggish. The data are further interpreted in a continuum mechanics, finite strain framework, in both one and two-dimensional geometries, whence stress and oxygen partial pressure exponents of the creep law are estimated. The stress exponent is indicative of power-law creep. The oxygen partial pressure exponent is consistent with a strain-rate limited by vacancy mediated self-diffusion of the slowest moving ion, suggesting a climb-controlled recovery process. Some samples are further characterized using SEM/EBSD which reveals signs of plastic deformation typical of recovery creep. The effect of oxygen pressure upon microstructure is discussed.

我们报告了在1500烧结二氧化铀上进行的一组压缩测试实验 $°$C，在恒定应变速率和受控氧分压下。宏观数据表明，在初始应变硬化阶段之后是准稳态阶段，在此期间应力水平的变化缓慢。在一维和二维几何结构中，在连续力学有限应变框架中进一步解释数据，据此估算蠕变律的应力和氧分压指数。应力指数表示幂律蠕变。氧分压指数与应变速率一致，该速率受空位介导的最慢运动离子的自我扩散限制，表明爬升控制的恢复过程。一些样品使用SEM / EBSD进行了进一步表征，显示出典型的恢复蠕变塑性变形迹象。