Solid State diffusion bonding is obtained by applying heat, well below the melting temperature of the metals, a static pressure which does not cause a macroscopic plastic deformation in the material, and a time required to form a metallurgical bond with atomic diffusion process. This process is used for aluminum alloys, high strength steels and titanium alloys in the aerospace industry to produce complex and inaccessible joints without localized distortion. Ability to diffusion bond titanium alloys is strongly needed to promote the use of superplastic forming technology. In the present work, the solid state diffusion bonding was carried out using specimens in Ti-6Al-4V and Ti-15V-3Cr-3Sn-3Al. The microstructure of the bonded interface indicates the diffusion bonding process is successful for both alloys. It is also shown that the diffusion bonding of a superplastic Ti-6Al-4V alloy is possible at the optimum superplastic condition so that two processes can be performed simultaneously. The structural integrity of diffusion bonding was evaluated with a hydraulic test of diffusion bonded part.

This paper gives an overview of current work in materials and manufacturing technology for aerospace application. Finding the best material to use for a particular application is not simple and it depends on many factors including mission requirements like performance and safety, design requirements, strength to density ratio, operating temperature, and material technology prospects like current state of affordable materials/processes technologies. Materials with high specific strength have long been popular with the aerospace industry, as aerospace vehicle made from such materials provide the required strength with less weight, thereby increasing payload and reducing operating cost. Typical examples are polymer matrix composite and aluminum-lithium alloys for aerospace structures. In liquid rocket propulsion systems, improved high-temperature capability offers the greatest performance payoff, with improved mechanical strength and lower weight also being important. For spacecraft, materials with improved resistance to radiation and atomic oxygen are required. Since before a material can be used in an aerospace system, it must be qualified for use, materials qualification procedure is also presented with an example of shared data.

High-temperature deformation behavior and microstructural evolution process of ELI Ti-6Al-4V alloy having martensite microstructure were investigated with the variation of strain, strain rate and temperature. A series of hot compression tests was carried out isothermally for martensite microstructure at the true strain range of 0.6 to 1.4, strain rate range of 10-3 s-1 to 1 s-1 and temperature range of 700 oC to 950 oC. The processing maps for martensite microstructures were constructed on the basis of dynamic materials model (DMM). At the strain rate higher than 10-2 s-1 and the temperature lower than 750 oC regions of flow instability such as adiabatic shear band and micro-cracking were observed. Also, after imposing an effective strain of ≈ 1.4, deformed microstructure showed the significant kinking/bending behavior of lamellae resulting in the dynamic globularization associated with the fragmentation of beta-phase. The effects of strain, strain rate and temperature for dynamic globularization were discussed based on the microstructure and efficiency of power dissipation.