Initial studies on the mechanical behaviour of oriented columnar grained tungsten-rhenium alloys

An initial study concerning the quasi-static mechanical behaviour of oriented columnar grained tungsten rhenium alloys has been made. The material investigated was supplied by the Russian Academy of Sciences and was made by plasma arc zone melting. Quasi-static tensile testing of samples with the grains oriented with a [ 1001 -respectively a [1 101-axis parallel with the tensile load direction was done. The chemical content of the material varied from pure tungsten to alloys with 1.9% and 4.8% rhenium. Crystallographic analysis showed that the crystal orientation of the samples in several cases contained low and high angle boundaries and thus deviated from the information given by the supplier. From the mechanical testing it is clear that the samples are very hard and brittle and several of the samples fractured at the transition between sample gauge and sample ends. The stress at fracture was typically 350-450 MPa at a strain of only 1-2%. From the limited number of samples tested it is therefore not possible to make any conclusive judgement of the material properties. It is known that the ductility of similar polycrystalline alloys can be greatly enhanced by an appropriate thermomechanical treatment. The sensitivity of the ductility to rhenium content, temperature, orientation and mechanical treatment should therefore be investigated. The report concludes with suggestions for further studies.