Effect of thermal heat loads on the microstructure of recrystallized double forged tungsten

Two recrystallized double forged W materials, one which was pre-heated up to 400 °C and exposed to 120 keV electrons during 100 pulses of 1 ms giving a total power of 1.26 GW/m2 and one as reference which was only pre-heated to 400 °C, were investigated with SEM and TEM to reveal the effect of the exposure on the microstructure. The reference material revealed that the selected material contains only some large angle grain boundaries and occasionally a few isolated dislocations. The e-beam exposure of the material resulted only in a deformation of the matrix. The surface has roughened and series of parallel ridges were observed in the SEM images. However, no cracks or other signs of material rupture were found. On a microscopic level the deformation manifested as an increased number of tangled dislocations and the reappearance of small angle tilt boundaries.