Alloys Development

This comprises both new catalysts and new alloys. Here, new fundamental knowledge is needed in order to fully understand the catalyst mechanism and, more importantly, hydride destabilization. Further discussions on some new directions are the subject of other chapters of this book (complex hydrides, amides, destabilized systems, aluminum hydride, nanoparticles and theoretical modeling). 

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Reactor-grade zirconium is essentially free of hafnium. Zircaloy(R) is an important alloy developed specifically for nuclear applications. Zirconium is exceptionally resistant to corrosion by many common acids and alkalis, by sea water, and by other agents. Alloyed with zinc, zirconium becomes magnetic at temperatures below 35oK. 

Alloys developed by processing through the investment casting process had high I 5r strength and design flexibiUty, which led to many further ... 

Alloy development in the former Soviet Union has produced alloys having strengths equivalent to IN-100 and Mar-M-200. Alloys developed in the United States and United Kingdom are also widely used in French aircraft engines. 

Lithium magnesium alloys, developed during World War 11, have found uses in aerospace appHcations. Lithium alters the crystallization of the host magnesium from the normal hexagonal stmcture to the body-centered cubic stmcture, with resultant significant decreases in density and increases in ductibiHty. 

Several of the Al—Li alloys developed in the 1980s contain both magnesium and copper. No quaternary Al—Cu—Li—Mg phase has been found in the alloys. The S -phase in addition to 5 and provides precipitation hardening. 

Properties. Most of the alloys developed to date were intended for service as fuel cladding and other stmctural components in hquid-metal-cooled fast-breeder reactors. AHoy selection was based primarily on the following criteria corrosion resistance in Hquid metals, including lithium, sodium, and NaK, and a mixture of sodium and potassium strength ductihty, including fabricabihty and neutron considerations, including low absorption of fast neutrons as well as irradiation embrittlement and dimensional-variation effects. Alloys of greatest interest include V 80, Cr 15, Ti 5... 

Nickel Steel Low-carbon 9 percent nickel steel is a ferritic alloy developed for use in cryogenic equipment operating as low as —I95°C (—320°F). ASTM specifications A 300 and A 353 cover low-carbon 9 percent nickel steel (A 300 is the basic specification for low-temperature ferritic steels). Refinements in welding and (ASME code-approved) ehmination of postweld thermal treatments make 9 percent steel competitive with many low-cost materials used at low temperatures. 

The incubation period varies widely depending on such factors as crack morphology, water chemistry, and temperature. However, experience in a wide variety of cooling water environments has shown that many stainless alloys develop noticeable attack within 6 months of first being exposed to water. It is rare to see attack initiating many years after equipment commissioning unless service conditions change in the interim. 

Lead-silver is primarily used in seawater and strong chloride-containing electrolytes. PbAg anodes are particularly suitable for use on ships and in steel-water constructions, especially as they are relatively insensitive to mechanical stresses. The original alloy developed by Morgan [8,9] consists of 1% Ag and 6% Sb, with the remainder Pb. It is represented as alloy 1 in Table 7-2. A similar alloy developed by Applegate [10] has 2% Ag and the remainder Pb. Another alloy... 

In the three decades following the publication of Rosenhain s book, the physieal science of metals and alloys developed rapidly, so that by 1948 it was possible for Robert Franklin Mehl (1898-1976) (see Smith 1990, Smith and Mullins 2001 and Figure 3.15), a doyen of American physical metallurgy, to bring out a book entitled A Brief History of the Science of Metals (Mehl 1948), which he then updated in the... 

On top of this alloy development, turbine blades for the past two decades have been routinely made from single crystals of predetermined orientation the absence of grain boundaries greatly enhances creep resistance. Metallic monocrystals have come a long way since the early research-centred uses described in Section 4.2.1. 

Mechanical properties of various titanium alloys are given in Table 5.16. In general the corrosion behaviour of those titanium alloys developed for the aircraft industry is very similar to that of unalloyed titanium . The addition of some alloying elements may increase resistance to one medium, but decrease it to others . 

The determination of polarisation curves of metals by means of constant potential devices has contributed greatly to the knowledge of corrosion processes and passivity. In addition to the use of the potentiostat in studying a variety of mechanisms involved in corrosion and passivity, it has been applied to alloy development, since it is an important tool in the accelerated testing of corrosion resistance. Dissolution under controlled potentials can also be a precise method for metallographic etching or in studies of the selective corrosion of various phases. The technique can be used for establishing optimum conditions of anodic and cathodic protection. Two of the more recent papers have touched on limitations in its application and differences between potentiostatic tests and exposure to chemical solutions. ... 

We used the common principles of quantitative analysis of additive properties of alloys developed in work [3].The following equation that describes the magnetic effect during the crystallization of the amorphous alloy Fes2Si2Bi6 was got ... 

Earlier work on systems such as Ni-Al-Cr reported in Sanchez et al. (1984b) used FP methods to obtain information on phases for which there was no experimental information. In the case of Ni-base alloys, the results correctly reproduced the main qualitative features of the 7 — 7 equilibrium but cannot be considered accurate enough to be used for quantitative alloy development. A closely related example is the work of (Enomoto and Harada 1991) who made CVM predictions for order/disorder (7 — 7 ) transformation in Ni-based superalloys utilising Lennard-Jones pair potentials. 

Of far greater significance, however, is the rapidly increasing use of lanthanum in high-temperature alloys. Developed originally to meet the demanding specifications for gas turbine manufacture, these alloys, which include both nickel-base and cobalt-base types, contain typically 200-400 ppm lanthanum. 

Bismuth-Manganese Alloy, developed at the Naval Ordnance Laboratory, White Oak,Md, is a suitable substitute for permanent magnets Alnico or the expensive Pt-Co alloy. The Bi -Mn alloy can be used in various electronic devices(Ref 3). The Bi-Mn alloy known as "Bismanol , prepd by powder metallurgy techniques, is claimed to possess a coercive force of 3000 oersteds(Ref 5)... 

The first metal alloy developed specifically for use in bone plates was vanadium steel, invented in about 1905. Over the next two decades, a number of other alloys and metals were tried as bone plate materials. In 1926, another alloy designed especially for bone plates was invented. It was a type of stainless steel consisting of 18 percent chromium and 8 percent nickel. Later the same year, a slightly modified form of the alloy was introduced, called I8-8SM0, containing a small amount of molybdenum. 

Following this introductory section, we will overview the development of random anisotropy models and discuss the origin of the magnetic softness in nanostructures. The nanostructural formation process and alloy development in the Fe-M-B-(Cu) alloys to which less attention has been addressed in the previous reviews, will be another focal point in this chapter. 

Titanium alloy systems have been extensively studied. A single company evaluated over 3000 compositions in eight years (Rem-Cru sponsored work at Battelle Memorial Institute). Alloy development has been aimed at elevated-temperature aerospace applications, strength for structural applications, biocompatibility, and corrosion resistance. The original effort has been in aerospace applications to replace nickel- and cobalt-base alloys in the 250—600°C range. The useful strength and corrosion-resistance temperature limit is ca 550°C. 

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