Anisotropic fracture behaviour and brittle-to-ductile transition of polycrystalline tungsten
Anisotropic fracture behaviour and brittle-to-ductile transition of polycrystalline tungsten
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多晶钨的各向异性断裂行为和脆塑转变
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
S. Weygand
中科院分区：
文献类型：
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作者：
D. Rupp;S. Weygand
用三点弯曲试验和电子显微镜研究了烧结和轧制多晶钨棒在−15 0℃~95 0℃范围内的断裂行为，特别注意了显微组织的影响。这项深入的研究证明了钨的结晶学和颗粒形状各向异性的积极影响。沿轧制方向提取的样品显示出比其他两个研究方向高一倍的断裂韧性和显着降低的脆韧性转变温度。此外，这些试件的断裂模式从穿晶断裂转变为沿晶断裂，裂纹偏转发生在270°C左右。在原位扫描电子显微镜断口测试中，可以阐明这种裂纹偏转的来源。最后提出了一个断裂力学模型，该模型正确地预测了两种断裂模式之间的转变，并给出了一个适用于解释实验断裂结果的能量判据。
The fracture behaviour of polycrystalline sintered and rolled tungsten rods was investigated from −150°C to 950°C by means of three-point bending tests and electron microscopy where special attention was drawn to the influence of the microstructure. This thorough investigation demonstrates the positive impact of the crystallographic and grain shape anisotropy in tungsten. Specimens extracted along the rolling direction exhibit twice as high fracture toughnesses and a significantly reduced brittle-to-ductile transition temperature than the other two investigated orientations. Furthermore, these specimens show a change in their fracture mode from transgranular to intergranular fracture with crack deflection occurring around 270°C. In an in situ SEM fracture test, the origin of this crack deflection could be clarified. Finally, a fracture mechanics model is presented which predicts correctly the transition between the two fracture modes and which gives an energy criterion suitable to interpret experimental fracture results.