Ductilitsation of tungsten (W) through cold-rolling

For tungsten, its tendency to fail at low temperatures by brittle fracture is a major limitation. This raises the question of how to make tungsten ductile.
The ductilisation approach presented in this contribution is the modification of the microstructure through cold-rolling. We define “ductilisation” as the concomitant improvement of the following properties: the brittle-to-ductile transition (BDT) temperature, the toughness or crack growth resistance, and the tensile ductility.
The BDT temperature has been determined by Charpy impact tests. The results show the following BDT temperatures: 675 °C (annealed), 375 °C (hot-rolled) and 125 °C (cold-rolled).
The crack growth resistance has been determined by the direct-current-potential-drop method. Cold-rolled tungsten plates show stable crack growth at room temperature and a fracture toughness, K_IQ, of 100 MPa(m)1/2 at a crack extension, Δa, of 0.3 mm.
The room-temperature ductility has been determined by tensile tests. The results show an increase of the total elongation to fracture, A_t, with decreasing rolling temperature: 3 % (cold-rolled at 800 °C), 4.19 % (cold-rolled at 600 °C).
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The results are discussed against the background of cold-rolling induced lattice defects.