Anisotropic fracture behaviour and brittle-to-ductile transition of polycrystalline tungsten

作者：Rupp D; Weygand S M^*

来源：Philosophical Magazine, 2010, 90(30): 4055-4069.

DOI：10.1080/14786435.2010.504198

• fracture toughness
• anisotropy
• polycrystalline tungsten
• brittle-to-ductile transition
• fracture mechanics modelling

The fracture behaviour of polycrystalline sintered and rolled tungsten rods was investigated from -150 degrees C to 950 degrees 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 degrees 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.

• 出版日期2010