Fine Structure of Heat-Resistant Titanium Alloys Welded Joints

The structural features of experimental heat-resistant multicomponent silicon-alloyed titanium alloys welded joints has been studied. They were produced by electron beam welding. Transmission electron microscopy has been used to study the fine structure of the heat-affected zone, the most problematic zone in welded joints. The internal structure of the beta-, alpha-, and alpha '-phases lamellar structures, their parameters, features of phase formation, and the density and distribution of dislocations were studied. Studies of thin foils made it possible to obtain detailed information on phase precipitates formed in a welded joint, which differ in size, morphology, stoichiometric composition and localization zones (along the boundaries of lamellar structures, in internal volumes, in the substructure). Analytical estimates of the differentiated contribution of structural phase factors and parameters to the level of strength characteristics and crack resistance of the metal in the heat affected zone of welded joints of titanium alloys show the positive effect of the dispersed plate substructure with a uniform distribution of the silicide and intermetallic phase nanoparticles.