![]() Plasma arc melting offered the ability to supply a cover gas to deal with vapor pressure issues as well as solidification control to help with macrosegregation in the melt and has successfully produced high quality ingots of the Ti-Ta alloys Vacuum arc remelting(VAR) was considered as a melting candidate and discarded due to density and vapor pressure issues associated with electron beam. Previous electron beam melting experience with these materials resulted, in extensive vaporization of the titanium and poor chemical homogeneity. Melting is further complicated by the high melting point of Ta(3020 C) and the relatively low boiling point of Ti(3287 C). The Ti-Ta alloys fall into this category with the density of tantalum 16.5 g/cc and that of titanium 4.5 g/cc. But, refractory metal alloys whose constituents possess very dissimilar densities, melting temperatures and vapor pressures pose significant difficulty and require specialized melting practices. Initial melting of these materials was performed in a small button arc melter with several hundred grams of material however, ingot quantities were soon needed. Liquid metal compatibility and density requirements have driven the research toward the Ti-Ta system with an upper bound of 60 wt% Ta-40 wt% Ti. Further, materials property constraints are dictated by a requirement to maintain low density e.g., less than the density of stainless steel. Los Alamos has several applications for high temperature, oxidation and liquid-metal corrosion resistant materials. Plasma arc melting of titanium-tantalum alloys Transmission data of a non-cadmium containing lead alloy with a melting point of 203 0 F was ascertained and is reported on ![]() ![]() However, proper handling procedures should be observed to avoid entry into the body via alternate pathways (e.g., ingestion or skin absorption). ![]() The results of this study indicate that the use of a vented hood as a means of reducing air concentrations of toxic metals above and near vessels containing low temperature melting point lead allows commonly used in construction of radiotherapy shields appears unjustifiable. In all instances, concentrations were much lower than the applicable occupational limits for continuous exposure. Samples were obtained for alloy temperatures of 200 0, 400 0, and 600 0 F. Fume concentrations were determined by collection on a membrane filter and analysis by atomic absorption spectrophotometry. International Nuclear Information System (INIS)ĭeterminations of airborne concentrations of lead, cadmium, bismuth, and tin were made above vessels containing a fusible lead alloy (158 0 F melting point) commonly used for construction of radiotherapy blocks. Airborne concentrations of toxic metals resulting from the use of low melting point lead alloys to construct radiotherapy shielding ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |