Classification of alloys

M. Click and G.M. Hieftje, Classification of alloys with an artificial neural network and multivariate calibration of Glow-Discharge emission spectra. Appl. Spectrosc., 45 (1991) 1706-1716. 

Divides in the Periodic Table. A particular scheme of subdivision of the Periodic Table has been presented by Stone (1979) and applied to the classification of alloying tendencies it is summarized in Fig. 4.7. In this figure, a number of vertical lines, termed divides , have been drawn in particular positions of the Table. These are so placed that any element near a divide, and on one side of it, will form a compound or compounds with a counterpart element at the other side of that divide or, in other words, will form compounds with a specific bonding mechanism. 

An attractive, semiempirical application of physical insight into alloy formation is found in classifications of alloy phase data into structure maps, quantum diagrams, and so on (see Structure Property Maps for Inorganic Solids) where a necessarily limited number of coordinates (one to three) must reflect the physical parameters determining the property of interest. An example is given below in the Pettifor map for Ti-Al intermetallics. Further developments in the mapping of intermetallics are due to Ceder. ... 

Classification of alloying elements with respect to scandium effect ... 

Taking into account physical-chemical interaction of alloying elements with A1 as well as with Sc, the following classification of alloying elements which includes 5 groups was proposed [7] ... 

AU the remarks mentioned above are applicable as well to the electrodeposition of alloys. Using Breimer s classification of alloy electrodeposition, e.g., equilibrium, regular, anomalous, etc., all existing combinations of deposition parameters and their influence on the alloy morphology are analyzed. Interestingly, certain features, which are not recognized in the electrodeposition of pure metals, are observed in the alloy depositiOTi processes. An example includes the spatiotemporal structures, which is discussed in this book. 

AWS) has issued specifications covering the various filler-metal systems and processes (2), eg, AWS A5.28 which appHes to low alloy steel filler metals for gas-shielded arc welding. A typical specification covers classification of relevant filler metals, chemical composition, mechanical properties, testing procedures, and matters related to manufacture, eg, packaging, identification, and dimensional tolerances. New specifications are issued occasionally, in addition to ca 30 estabUshed specifications. Filler-metal specifications are also issued by the ASME and the Department of Defense (DOD). These specifications are usually similar to the AWS specification, but should be specifically consulted where they apply. 

Table 3. Susceptibility Classification of Commercial Wrought Aluminum Alloys in Plate Form—Short Transverse Orientation ...

Many metals and metallic alloys show martensitic transformations at temperatures below the melting point. Martensitic transformations are structural phase changes of first order which belong to the broader class of diffusion js solid-state phase transformations. These are structural transformations of the crystal lattice, which do not involve long-range atomic movements. A recent review of the properties and the classification of diffusionless transformations has been given by Delayed... 

Metals and alloys removal of corrosion products from corrosion test specimens Metals and alloys atmospheric corrosion testing general requirements for held tests Corrosion of metals and alloys. Classification of corrosivity of atmospheres Corrosion of metals and alloys. Guiding values for the corrosivity categories of atmospheres... 

F. C. Frank, J. S. Kasper, Complex alloy structures regarded as sphere packings. I Definitions and basic principles, Acta Crystallogr. 11 (1958) 184. II Analysis and classification of representative structures, Acta Crystallogr. 12 (1959) 483. 

F. C. Frank and J. S. Kasper, Complex Alloy Structures Regarded as Sphere Packings. II. Analysis and Classification of Representative Structures, Acta Cryst., 12, 483 (1959). 

This is an on-going project aimed at examining the T/D characteristics of metals and alloys in a marine medium in seven- and twenty eight-day tests. The data obtained to date on seven-day tests of cuprous oxide (Cu20) and nickel metal powder (Ni) provides useful comparisons with those reported earlier for the freshwater OECD 203-based media at pH 6 and 8 (Skeaff Hardy 2005) and insight into the behaviour of metal-bearing substances used in commerce under marine conditions of the T/DP. The data supports an approach directed to the eventual adaptation, validation and application of the OECD T/DP to marine systems for the purposes of marine hazard classification of metals, metal compounds and alloys. 

The situation in the solid state is generally more complex. Several examples of binary systems were seen in which, in the solid state, a number of phases (intermediate and terminal) are formed. See for instance Figs 2.18-2.21. Both stoichiometric phases (compounds) and variable composition phases (solid solutions) may be considered and, as for their structures, both fully ordered or more or less completely disordered phases. This variety of types is characteristic for the solid alloys. After a few comments on liquid alloys, particular attention will therefore be dedicated in the following paragraphs to the description and classification of solid intermetallic phases. 

Just as it is effective in the other fields of inorganic descriptive chemistry, the Periodic Table is an essential reference point in intermetallic chemistry too. The general alloying characteristics of the different metals, their reactivity towards the other metals, the variety of their intermetallic derivatives usually are very complex and cannot be easily explained and rationalized on the basis of a few concepts and data. Nevertheless a sound first criterion for a description and classification of the intermetallic behaviour of the various metals lies in their position in the Periodic Table. 

Comments on some trends and on the Divides in the Periodic Table. It is clear that, on the basis also of the atomic structure of the different elements, the subdivision of the Periodic Table in blocks and the consideration of its groups and periods are fundamental reference tools in the description and classification of the properties and behaviour of the elements and in the definition of typical trends in such characteristics. Well-known chemical examples are the valence-electron numbers, the oxidation states, the general reactivity, etc. As far as the intermetallic reactivity is concerned, these aspects will be examined in detail in the various paragraphs of Chapter 5 where, for the different groups of metals, the alloying behaviour, its trend and periodicity will be discussed. A few more particular trends and classification criteria, which are especially relevant in specific positions of the Periodic Table, will be summarized here. 

There are three anions that may loosely claim to be nitrides. Pentazolides (salts of cyclic N ) will all be explosive. Some azides (salts of N3) fall just short of being explosive but all are violently unstable. The true nitrides, nominal derivatives of N3-, are more various. In addition to some ionic structures, there are polymeric covalent examples, and some monomeric covalent ones, while most of those of transition metals are best considered as alloys. Several are endothermic and explosive, almost all are thermodynamically very unstable in air with respect to the oxide. Many are therefore pyrophoric if finely divided and also may react violently with water and, more particularly, acids, especially oxidising acids. A few are of considerable kinetic stability in these circumstances. There is no very clear classification of probable safety by position in the periodic table but polymeric and alloy structures are in general the more stable. Individual nitrides having entries ... 

ISO 11844-3.-Corrosion of metals and alloys. Classification of corrosivity of indoor atmospheres. Measurement of environmental parameters affecting indoor corrosivity. 

A. Classification of the Reactions on Metals and General Description of Alloying Effects... 

The casting alloy products comprise sand castings, permanent mold castings, and die castings. Aluminum is the basic raw material for more than 20,000 businesses in the United States. Aluminum is an indispensable metal for aircraft, for example. See Fig. 3. Representative aluminum alloys for a broad classification of uses is given in Table 1. 

A.H. Deutchman and R.J. Partyka (Beam Alloy Corporation observe, "Characterization and classification of thin diamond films depend both on advanced surface-analysis techniques capable of analyzing elemental composition and microstructure (morphology and crystallinity), and on measurement of macroscopic mechanical, electrical, optical and thermal properties. Because diamond films are very thin (I to 2 micrometers or less) and grain and crystal sizes are very small, scanning electron microscopy... 

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