Alloy types

Boron forms B—N compounds that are isoelectronic with graphite (see Boron compounds, refractoryboron compounds). The small size also has a significant role in the interstitial alloy-type metal borides boron forms. Boron forms borides with metals that are less electronegative than itself including titanium, zirconium, and hafnium. 

Gallium-Based Alloys. A gaUium-based alloy has been kitroduced commercially ki Japan as a substitute for dental amalgam, but similar alloy types have previously been associated with abnormal cellular reactions and are not much used elsewhere nickel— gallium alloys have produced carckiomas ki rats (139). The corrosion resistance of the gallium alloys is also marginal. 

Conveyors may be of parallel-chain, mat, slat, woven wire-mesh belt, or cast-alloy type. Automatic tensioning devices are used to maintain belt tension during heating and cooung. The product may rest directly on the conveyor or on special supports built into it. RoUer-conveyors are used for large pieces. Flame curtains are provided for sealing the ends and for protection of special treating atmospheres. 

The addition of molybdenum to the austenitic alloy (types 316, 316L, 317, and 317L) provides generally better corrosion resistance and improved resistance to pitting. 

The ferritic chromium steels (chromium is the principal alloying element) are the most economical for very lightly loaded high-temperature situations. However, they are inadequate when creep must be accounted for. Austenitic steels are often recommended for such conditions. The 17% chromium alloys (Type 430) resist scaling up to 800°C and 25% alloy (Type 446) up to llOO C [21]. 

Other more highly alloyed types, of which a typical example is given in Table 3.11, have the designation of precipitation hardening martensitic. Relative to the simple 13% chromium types they have a substantial nickel content and low carbon with additions from molybdenum, copper, aluminium, titanium and niobium. These offer improved corrosion resistance, strength, toughness, weldability and fabrication properties, but not always together. 

The individual characteristics and uses of the basic grades of the austenitic irons are given in Table 3.55. The major uses for these materials occur in the handling of fluids in the chemical and petroleum industries and also in the power industry and in many marine applications. The austenitic irons are also used in the food, soap and plastics industries where low corrosion rates are essential in order to avoid contamination of the product. Ni-Resist grades Type 2, 3 or 4 are generally used for such applications but the highly alloyed Type 4 Ni-Resist is preferred where low product contamination is of prime importance. 

SI temperatures are given for a number of tests, including some carbon and low-alloy types for comparison, in Table 7.8. As well as the types listed in Table 7.7, a selection of creep-resisting grades is included. In addition some of the special stainless steels (see Section 3-3) are also included to demonstrate the effects of some other alloying elements. 

Other heavy metal impurities (especially copper and nickel) have similar adverse effects on all generic alloy types. In their case sequestering has not proved successful and control of input quality is used to keep their concentration acceptably low. ... 

When Mg is alloyed with Al, for use in some incendiary, tracer and photoflash compns, the requirements of the US Armed Forces are given in the Mil Spec entitled, Magnesium-Aluminum Alloy, Powdered (Ref 1). It covers two types of Mg-Al alloy, Type A (50/50), and Type B (65/35)... 

The comparison of the data from Figure 4 shows that the pure magnesium (99.99%) is the most suitable material to be used as anode in magnesium-air cells with NaCl-electrolyte. The magnesium alloy type... 

C.E. Lundin, F.E. Lynch, Modification of hydriding properties of AB5 alloy type hexagonal alloys through manganese substitution, Proceedings of the Miami International Conference Alternate Energy Sources, United States, 5-7 December 1977. University of Miami, (1978)... 

Compounds discussed in some detail in the text hypothetical alloy type... 

Fig. 24. Structure of kotoite, Mg3(B03)2- It is an anion-stuffed version of the W2C0B2 alloy type...

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