Additive manufacturing of titanium alloys by cold spraying onto Al7075

The aluminum alloy Al7075 is commonly used in aircraft industry due to its high mechanical resistance to weight ratio. Nevertheless when the structure is being serviced upon the severe environmental conditions or loads degradation mechanisms could often been found in the material. To improve its behavior the cold spray process with various titanium powders (e.g. CP Ti, Ti-64) deposited onto Al7075 was investigated. The spraying of angular titanium powder was performed in the presence of nitrogen and helium supplied at process parameters (temperature, pressure), which were the maximum values attainable by the CS system used. The deposits were sprayed while maintaining a standoff distance in the range from 20 to 100 mm increased by 10 mm. The experimental data indicated that the deposition efficiency had increased significantly with increasing standoff distance. The coating porosity first decreased to minimum 0.6% and then increased significantly to 9.8%. The mechanical properties of the coatings reached the highest values when the porosity was minimum. No new phases were reported in the cold sprayed titanium coatings when compared with the starting feedstock. The same process parameters were transferred to Ti- 6Al-4V coral like powder deposition process. The shear strength between Ti coating material and Al7075 substrate was measured. Additionally the tensile strength of the deposit only, previously disintegrated from the substrate, was checked out. The data obtained indicate that the consolidation of Ti powder with Al7075 substrate made by cold spray could be served for both: materials integration and building a component by materials disintegration, where Al substrate is removed on spraying and machining; and simply used as a technological support for additive manufacturing of a self-standing real life component.