Search

In the present study, a commercially pure (CP) Ti and Ti-Re alloys containing 2 and 4 wt% of Re were manufactured by selective laser melting (SLM) and characterized in terms of microstructure, strength and fatigue crack propagation resistance. On the contrary to a homogenous lath-type martensitic a' microstructure with no signs of directional solidification observed for CP Ti, the Re addition led to development of columnar prior v grains oriented along building direction with a much finer acicular a' martensite in Ti-Re alloys. The width of martensitic a' needles decreased with increasing Re content. Re affected also the formation of different phase constituents. The presence of o phase precipitates as well as residual undissolved Re particles was noticed in Ti-Re alloys. Ti-Re alloys exhibited also the substantially increased ultimate tensile strength and drastically reduced ductility in comparison to CP Ti. These findings have been discussed in the paper considering the highly refined acicular a' martensitic structure, the increased oxygen content as well as the presence of strengthening o phase precipitates in Ti-Re alloys. Finally, the brittleness of Ti-Re alloys caused the deterioration of their fatigue crack propagation resistance.

Selective laser melting (SLM) is an additive manufacturing process that enables novel alloy production by combining metals with significantly different physical properties. In this paper, the hot corrosion behavior of Ti-Re alloys fabricated by SLM was studied in a mixture of Na2SO4 and NaCl salts at 600 °C. The morphology and composition of the corrosion products were characterized by scanning electron microscopy with energy-dispersive X-ray spectroscopy and X-ray diffraction to understand the degradation mechanisms. It has been shown that the hot corrosion resistance of Ti-Re alloys was influenced by the chemical inhomogeneity of the oxide scale resulting from the presence of rhenium particles undissolved during the SLM process.

Equal Channel Angular Pressing (ECAP) is one of the methods which allows to obtain ultrafine-grained and nanocrystalline metallic materials. It is well known that microstructure of materials pro-cessed by ECAP in not very stable. There were published many experimental and theoretical evidences of this fact obtained by various methods such as microstructure observations, properties measurement and computer modeling. The aim of presented paper was to investigate the thermal stability of microstructure and mechanical properties of the Al 5483 alloy processed by ECAP. As a result of performed investigations it was concluded that accumulated plastic deformation has no influence on the thermal stability of Al 5483 alloy processed by ECAP. It was also found that properly chosen parameters of ECAP and subsequent annealing allows to produce materials with high strength and plasticity. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35435