Layered Structures of Ti-6Al-4V Alloy and Metal Matrix Composites on Its Base Joint by Diffusion Bonding and Friction Welding

Metallic layered structures demonstrate an advanced set of characteristics that combine different properties not found within homogenous bulk materials. Powder metallurgy (PM) is proven to be the most efficient way of fabrication of layered structures, including highly rated structures of Ti alloys. Residual porosity, however, remains one of the biggest problems of titanium-based PM products and this can adversely affect the mechanical properties and performance of the structural parts. Post-sintering hot deformation is a common way to control the porosity of metallic materials. Traditional thermomechanical processing like hot rolling, however, could not be applied on multi-layered structures due to the disparity of the different layers’ plastic flow. Separate processing of high performance individual layers to reach their best parameters, followed by post processing bonding of the mating subcomponents is a credible pathway for fabrication of the layered materials with highly optimized properties of each individual layer. In this study we used diffusion bonding (DB) and friction welding to join the parts made of Ti-6Al-4V alloy and metal matrix composites on the base of this alloy reinforced with 10% of either TiB or TiC. Parts were fabricated using blended elemental PM. Different protocols were used to join the materials: DB welding via rotational friction (RFW) and linear friction (LFW) as well as different geometries of mating subcomponents were tested. Structure characterization of the joints using light optical microscopy, SEM, EDS, EBSD as well as mechanical tests were performed. All used protocols were generally successful in bonding the parts made of Ti-64 alloy and composites on its base. The potential of DB, RFW and LFW of Ti-6Al-4V alloy and its MMC are discussed

The role of modeling in the development of advanced processes for metallic aerospace alloys

The application of various modeling techniques in the design and control of a number of emerging processes for aerospace alloys is summarized. These techniques include those that are based on melting and solidification (electron-beam cold-hearth melting, laser deposition), deformation (severe-plastic deformation), rapid heat treatment (dual-microstructure processing), and metal removal (distortion-free machining, high-speed machining). The models that have been developed and applied to these processes include those that are largely phenomenological (e.g., continuum FEM codes) or mechanism based. The key elements of models for various processes, important analytical/numerical results, and how these results are or can be used for manufacturing design are summarized. Challenges for the further development and application of the models for industrial processes are also described. These include refinement of the physics-based understanding of the processes and measurement of various material properties that are needed to apply the models in a real-world manufacturing environment.X114sciescopuskciothe