Development and Producing of Bulk Nanostructured Refractory Metals using Equal Channel Angular Pressing and Theremomechanical Treatment

摘要

The aim of current investigations has been producing of ultrafine- grained (UFG) structure in refractory and hard-to-deform metals - W and Ta - by means of severe plastic deformation (SPD), using equal-channel angular pressing (ECAP) and further thermo-mechanical treatments. The results of investigations on development and application of ECAP for microstructure refinement in W and are presented. Microstructure of the processed billets has been studied by the methods of optical and transmission electron microscopy (TEM) and the X-ray structural analysis. The influence of the number of passes on W microstructure evolution during the process of ECAP has been investigated. It has been shown, that the nanostructured state with a mean grain size equal to 100-200 nm is formed through additional high pressure torsion (HPT) in ECAP-processed W and . Fabrication of bulk W and Ta billets with UFG structure has a strong influence on mechanical behavior of processed metals.