Alloy titanium-base

Titanium-Based Casting and Wrought Alloys. Titanium-based alloys offer an attractive alternative to gold alloys and to the base-metal alloys that contain nickel or chromium. On a volume basis the cost of titanium is roughly comparable to that of the chromium-containing alloys, but the price of titanium tends to be more stable because its ores are abundant and widely distributed (see Titaniumand titanium alloys). 

High-purity metals and superalloys are required for the aeronautics, electronics, instruments, space, and defense industries the raw materials are at present imported. Primarily, these special metals include nickel-and cobalt-based superalloys, high-strength iron-based alloys, titanium-based alloys, controlled-expansion alloys, and magnetic materials. Keeping in view the importance of these metals and alloys and the expertise available in India for making them, the NCST has identified two projects for their development the setting up of a special metal and superalloys plant and the development of controlled-expansion alloys. 

The materials currently used in the production of medical devices include stainless steels, cobalt-base alloys, titanium-base alloys, platinum-base alloys, and nickel-titanium alloys. Steels were the first modern metallic alloys to be used in orthopedics and initial problems with corrosion were overcome by modifying the composition of the steel with the addition of carbon, chromium, and molybdenum. Carbon was added at low concentrations (ca. 0.03-0.08%) to initiate carbide formation, while the addition of chromium (17-19%) facilitated the formation of a stable surface oxide layer and the presence of molybdenum (2.0-3.0%) was found to control corrosion. The compositions of stainless steels used can vary widely. Table V shows the limits for the chemical compositions of three different alloys containing eleven different elements together with the mechanical properties for the samples after annealing and cold working. 

Besides the material based characteristics, the difference of density of the used particle/substrate combination is a very important criterion. The difference of density influences the contrast of the radiographic tests. Tungsten carbides were used as mechanically resistant particles and titanium based alloys as substrate. The substrate material is marked by an advantageous relation of strength to density. This material is often used in aeronautics, astronautics, and for modification of boundary layers. The density of tungsten carbide (15.7 g/cm ) is about 3.5 times higher than the density of titanium (4.45-4.6 g/cm ). 

Table 15. Properties of Titanium Aluminides, Titanium-Base Conventional Alloys, and SuperaHoys ...

Molybdenum, an unusually versatile alloying element, imparts numerous beneficial properties to irons and steels and to some alloy systems based on cobalt, nickel, or titanium. Comprehensive summaries of uses through 1948 (24) and 1980 (25) are available. 

Buchanan, R. A. and Lemons, J.E. In Vivo Corrosion-Polarisation Behavior of Titanium-base and Cobalt-base Surgical Alloys , Transactions of the Eighth Annual Meeting of the Society for Biomaterials, Orlando, Florida (1982)... 

Detailed consideration of the structure of many of the advanced and complex alloys which are of considerable technological importance (high-strength titanium alloys, nickel-base superalloys, etc.) is beyond the scope of this section, other than to point out that no new principles are involved. Certain titanium alloys, for example, exhibit a martensitic transformation, while many nickel-base superalloys are age hardening. Similarly, cast irons, although by no means advanced materials, are relatively complex they are considered in Section 1.3 where graphitisation is discussed. 

This process uses a moving laser beam, directed by a computer, to prepare the model. The model is made up of layers having thicknesses about 0.005-0.020 in. (0.012-0.50 mm) that are polymerized into a solid product. Advanced techniques also provides fast manufacturing of precision molds (152). An example is the MIT three-dimensional printing (3DP) in which a 3-D metal mold (die, etc.) is created layer by layer using powdered metal (300- or 400-series stainless steel, tool steel, bronze, nickel alloys, titanium, etc.). Each layer is inkjet-printed with a plastic binder. The print head generates and deposits micron-sized droplets of a proprietary water-based plastic that binds the powder together. 

Commercial alloys composition, nomenclature. A simple and general way of identification of a commercial alloy (or of a group of similar alloys) consists of a label which gives (as rounded values) the mass% contents of the main components indicated by their chemical symbols. The alloy, for instance, Ti-6A1-4V, is a titanium-based alloy typically containing 6 mass% aluminium and 4 mass% vanadium. 

Researchers have tried to fabricate plates using many different metals— mainly, stainless steel, aluminum alloys, titanium alloys, nickel alloys, copper alloys, intermetallic alloys, and metal-based composites such as carbon fiber-reinforced aluminum alloys, carbon fiber reinforced copper alloys, etc. [26]. Although Ta, Hf, Nb, Zr, and Ti metals show good corrosion resistance and chemical stability [6], the cost of fhese metals is too high for them to be used as materials in metal plates. That is why relatively cheaper iron-based alloys, particularly stainless steel, have been popularly studied as plate material. In the following secfions, we will infroduce sfainless sfeel (SS) and SS plates, which have been extensively investigated and show promise for the final applications [6,11]. 

Figure 5.110 Variation of tensile strength with temperature for some titanium-based alloys and composites. Reprinted, by permission, from M. Schwartz, Composite Materials Handbook, 2nd ed., p. 2.111. Copyright 1992 by McGraw-Hill, Inc.

The titanium-base alloys are considerably stronger than aluminum alloys and superior to most alloy steels in several respects. Several types are available. Alloying metals include aluminum, vanadium, tin, copper, molybdenum, and chromium. 

More recently magnesium-base, iron-base, and zirconium-titanium-base alloys have been developed that do not require such rapid cooling. In 1992, W. L. Johnson and co-workers developed the first commercial alloy available in bulk form Vitreloy 1, which contains 41.2 a/o Zr, 13.8 a/o Ti, 12.5 a/o Cu, 10 a/o Ni, and 22.5 a/o Be. The critical cooling rate for this alloy is about 1 K/s so glassy parts can be made with dimensions of several centimeters. Its properties are given in Table 15.3. 

Abstract The current state of production, certification and use of standard samples of aluminium-and titanium-based alloys with specified contents of gas impurities is described. A list of the certified standard samples with a specified gas impurity content which are available in Russia is presented. 

A titanium base alloy as set forth in claim 1 having up to 0.1% iron, balance titanium. 

Rebak, R.B., Corrosion of Non-Ferrous Alloys, Part I Nickel-, Cobalt-, Copper-, Zirconium-and Titanium-Base Alloys, Corrosion and Environmental Degradation, Vol. II, Wiley-VCH, Weinheim, p. 69, 2000. 

Of all the 115 elements listed in the Periodic Table, 70% exhibit metallic character. Since the discovery of copper and bronze by early civilizations, the study of metals i.e., metallurgy) contributed to most of the early investigations related to materials science. Whereas iron-based alloys have long been exploited for a variety of applications, there is a constant search for new metallic compositions that have increasing structural durability, but also possess sufficiently less density. The recent exploitation of titanium-based alloys results from this effort, and has resulted in very useful materials that are used for applications ranging from aircraft bodies to golf clubs. Indeed, there are many yet undiscovered metallic compositions that will undoubtedly prove invaluable for future applications. 

Most metallic biomaterials fall into one of four categories stainless steels, titanium and titanium-based alloys, cobalt-chromium alloys, and amalgams. Additionally, research is under way on a number of... 

Past year development of new titanium alloys was based on possibility of using phase transformations and on explorations to study alloying effect on these transformations. A wide range of a-, (3- and (a+P)-alloys for various applications was created. The most widely known alloy is Ti-6A1-4V. The... 

The titanium-based composites with discontinuous reinforcement are attractive materials for a wide range of applications because of their high specific strength and stiffness and good fracture-related properties. Mechanical behavior of these materials depends strongly on both composition and microstructure of matrix and type, size and volume fraction of reinforcing phase. Hot plastic deformation is a powerful tool enhancing mechanical properties of titanium alloys. 

The densities of the stoichiometric compositions were determined to 4.32 g/cm3 for Ti5Si3 and 4.07 g/cm3 for TiSi2. Both compounds possess lower densities than titanium base alloys. A good correlation between binding energies, melting temperatures and microhardness of the investigated silicides is shown in table I. 

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