Guillen Donna Post, Toloczko Mychailo B, Prabhakaran Ramprashad, Zhu Yuanyuan, Lu Yu, Wu Yaqiao
Idaho National Laboratory, 995 University Blvd., Idaho Falls, ID 83401, USA.
Pacific Northwest National Laboratory, 902 Battelle Blvd., Richland, WA 99354, USA.
Materials (Basel). 2023 Aug 8;16(16):5518. doi: 10.3390/ma16165518.
A thermal neutron absorber material composed of AlHf particles in an aluminum matrix is under development for the Advanced Test Reactor. This metal matrix composite was fabricated via hot pressing of high-purity aluminum and micrometer-size AlHf powders at volume fractions of 20.0, 28.4, and 36.5%. Room temperature tensile and hardness testing of unirradiated specimens revealed a linear relationship between volume fraction and strength, while the tensile data showed a strong decrease in elongation between the 20 and 36.5% volume fraction materials. Tensile tests conducted at 200 °C on unirradiated material revealed similar trends. Evaluations were then conducted on specimens irradiated at 66 to 75 °C to four dose levels ranging from approximately 1 to 4 dpa. Tensile properties exhibited the typical increase in strength and decrease in ductility with dose that are common for metallic materials irradiated at ≤0.4T. Hardness also increased with neutron dose. The difference in strength between the three different volume fraction materials was roughly constant as the dose increased. Nanoindentation measurements of AlHf particles in the 28.4 vol% material showed the expected trend of increased hardness with irradiation dose. Transmission electron microscopy revealed oxygen at the interface between the AlHf particles and aluminum matrix in the irradiated material. Scanning electron microscopy of the exterior surface of tensile tested specimens revealed that deformation of the material occurs via plastic deformation of the Al matrix, cracking of the AlHf particles, and to a lesser extent, tearing of the matrix away from the particles. The fracture surface of an irradiated 28.4 vol% specimen showed failure by brittle fracture in the particles and ductile tearing of the aluminum matrix with no loss of cohesion between the particles and matrix. The coefficient of thermal expansion decreased upon irradiation, with a maximum change of -6.3% for the annealed irradiated 36.5 vol% specimen.
一种由铝基体中的AlHf颗粒组成的热中子吸收材料正在为先进试验反应堆进行研发。这种金属基复合材料是通过对高纯度铝和微米尺寸的AlHf粉末进行热压制成的，其体积分数分别为20.0%、28.4%和36.5%。对未辐照试样进行的室温拉伸和硬度测试表明，体积分数与强度之间存在线性关系，而拉伸数据显示，在体积分数为20%至36.5%的材料之间，伸长率大幅下降。对未辐照材料在200°C下进行的拉伸试验也显示出类似趋势。然后对在66至75°C下辐照至约1至4 dpa的四个剂量水平的试样进行了评估。拉伸性能表现出强度随剂量增加而典型增加、延展性随剂量降低的趋势，这对于在≤0.4T下辐照的金属材料来说是常见的。硬度也随中子剂量增加。随着剂量增加，三种不同体积分数材料之间的强度差异大致保持不变。对28.4体积%材料中的AlHf颗粒进行的纳米压痕测量显示，硬度随辐照剂量增加呈现预期趋势。透射电子显微镜显示，辐照材料中AlHf颗粒与铝基体之间的界面处存在氧。对拉伸试验后试样外表面进行的扫描电子显微镜观察表明，材料的变形是通过铝基体的塑性变形、AlHf颗粒的开裂以及在较小程度上基体与颗粒分离的撕裂来实现的。一个辐照的28.4体积%试样的断口表面显示，颗粒发生脆性断裂，铝基体发生韧性撕裂，颗粒与基体之间没有粘结力损失。辐照后热膨胀系数降低，退火后的辐照36.5体积%试样的最大变化为-6.3%。
