Mechanical properties and microscopic analysis of sintered rhenium subjected to monotonic tension and uniaxial fatigue

Some reports on the mechanical testing of pure rhenium can be found in the literature. However, very few studies have been published regarding the fatigue properties of rhenium. To gain new knowledge on this subject, the present research aimed to determine mechanical properties in monotonic tension, hardness, and stress-controlled fatigue tests of sintered rhenium. The results of the basic mechanical tests are in agreement with data in the literature. The determined exploratory S-N fatigue curve for pure, sintered rhenium is a unique result, and it cannot be compared with others. Based on the monotonic tests data, estimated S-N curves were also determined. The comparison of the experimental curve and the estimated curves showed the usefulness of approximation methods to estimate the fatigue properties of rhenium. Considering the high cost of conducting research on rhenium, this is especially important for engineering design. Subsequently, microscopic fracture analysis and microstructure evolution observation were performed. Microscopic observations were made using a light optical microscope and a scanning electron microscope. Based on the performed metallographic analyses, it was found that under fatigue and monotonic loadings, cracks propagated along the grain boundaries, and the pores present in the material did not affect this process. It was confirmed that the basic deformation mechanism in sintered rhenium is twinning. To sum up, the present work provides new data on the strength properties of rhenium and helps to better understand the deformation and damage processes of this metal.