【摘要】 采用电解渗氢法制备出氢含量为60mg/g的压力管材料Zr-2.5Nb合金。利用X射线衍射仪（XRD）、金相显微镜（OM）、透射电子显微镜（TEM）研究了Zr-2.5Nb合金微观结构,采用扫描电镜（SEM）观察了Zr-2.5Nb合金氢致延迟开裂（DHC）断口形貌。结果表明:Zr-2.5Nb合金基体为密排六方结构的a-Zr相,远离裂纹尖端区域晶粒较大（大于5mm）,裂纹尖端对应区域的基体晶粒较小（1mm左右）;面心立方结构δ-ZrH_1.66呈条片状平行于轧制方向分布;体心立方结构的第二相Nb颗粒尺寸为50⁵00 nm,在晶粒内部均匀分布,晶界附近成串状分布;试验温度为250℃时,预制疲劳裂纹平行于轧制方向的试样,裂纹呈现步进式生长,每步生长的距离大致相当于氢化物的尺寸,约为20mm。更多还原

【Abstract】 Zr-2.5Nb alloy with hydrogen content 60 mg/g was produced by electrolytical hydrogenation. The microstructure of the Zr-2.5Nb alloy was investigated using X-ray diffraction（XRD）, optical microscope（OM）, and transmission electron microscopy（TEM）. Fractography was performed on the delayed hydride cracking（DHC） fracture surfaces using scanning electron microscopy（SEM）. The results have shown that the matrix of the Zr-2.5Nb alloy is close-packed hexagonal structure, and the grain size is larger（more than 5 mm） away from crack-tip, but smaller（approximately 1um） near the tip of the crack. The hydride with stripy feature is δ-ZrH_1.66 of face-centered cubic structure; it distributes parallel to the rolling direction. The second phase Nb particles, which have the body centered cubic, varying from 50 nm to 500 nm in size, are roundly shaped, appear quite homogeneously distributed in the inner region of the grains, but they were cluster on grain boundaries. When the preset crack direction is parallel to the rolling direction and the test temperature is 250°C, DHC fracture growth process is an intermittent process. Each step of crack propagation results in the crack extension by a distance approximately the length of the hydride, and the length of the hydride is about 20 mm.更多还原