A Heat Treatment to Produce a Coarse-α-Particle Size in Ti–6Al–4V

Metallurgical and Materials Transactions A - A heat-treatment method to develop a coarse-α-particle size in Ti–6Al–4V with a fully-globular (equiaxed) microstructure was developed....     

Effects of an Ingot Smelting Method and Pressure Treatment Modes on the Structure of Deformed TiNi-Based Alloy Semi-Finished Products

Metallurgist - It is shown that the pressure treatment of titanium nickelide alloys should be carried out in two stages. At the first stage, ingots are deformed in order to transform the brittle...     

Metallurgical Features of Plasma Surfacing Repair of Magnesium Alloys

Metallurgist - Results are provided for studying formation of the structure and properties of products made of high-strength light alloy ML5 of the magnesium-aluminum-manganese-zinc system using...     

Sulfur in chromia

The solubility of sulfur in chromia has been studied in H₂-H₂O-H₂S tagged with³⁵S at 973 and 1173 K at low oxygen and sulfur partial pressures typical for coal gasification-systems. For monocrystalline samples, it has been shown that sulfur-containing species are only present adsorbed on the surface of the specimens and can be removed by ultrasonic cleaning in acetone. The surface coverage after 4 weeks of exposure to H₂-H₂O-H₂S was between 2.8 and 19.3% of a monolayer. In polycrystalline chromia, sulfur was located only in pores and cracks of the sample. In dense, compact areas of the specimens the solubility of sulfur was below the detection limit of autoradiography, which was estimated to be better than 0.17 ppm.     

Macrosegregation in ESR and VAR Processes

The method of heat generation, heat transfer characteristics, and ingot structure are very different in the VAR and ESR processes, which result in different tendencies and mechanisms for macrosegregation formation in forged IN-718. Freckles are niobium rich and can be generated in both ESR and VAR, with higher incidence in ESR than VAR. White spots are niobium lean and can only be found in VAR-processed materials. Freckles are indige-nous in nature, and result from the flow of solute-rich interdendritic liquid in the mushy zone during solidification. The most plausible cause for white spots is exogenous material, which remains unmelted, falling into the molten pool. The best way to minimize the formation of freckles is to improve the ingot heat transfer rate, a more difficult task in ESR than in VAR.     

Diffusion in gold and Au-Ag alloys

The self-diffusion coefficients of gold in pure gold and alloys of gold and silver have been measured over a range of temperatures. Chemical interdiffusion coefficients have been measured on pure metal and incremental couples, but are of lower accuracy because of the development of porosity. The results are compared with earlier work and internally on the basis of Darken’s equations.