Alloy powders

Above 40 wt % hydrogen content at room temperature, zirconium hydride is brittle, ie, has no tensile ductiHty, and it becomes more friable with increasing hydrogen content. This behavior and the reversibiHty of the hydride reaction are utilized ki preparing zirconium alloy powders for powder metallurgy purposes by the hydride—dehydride process. The mechanical and physical properties of zirconium hydride, and thek variation with hydrogen content of the hydride, are reviewed in Reference 127. 

Metallic cobalt, metallic nickel and an alloy powder containing 66-67% nickel, 13-16% chromium and 7% iron... 

Significant advances have also been made by forging titanium alloy (T1-6A1-4V) and cobalt chromium alloys cold working multiphase cobalt based alloys and by hot isostatically pressing cobalt chromium alloy powders. The property values claimed by the manufacturers are far in excess of the minimum values specified in the British, American and International Standards... 

The thickness of amorphous alloys is dependent upon production methods. Rapid quenching from the liquid state, which is the most widely used method, produces generally thin amorphous alloy sheets of 10-30 tm thickness. This has been called melt spinning or the rotating wheel method. Amorphous alloy powder and wire are also produced by modifications of the melt spinning method. The corrosion behaviour of amorphous alloys has been studied mostly using melt-spun specimens. 

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)... 

Material requirements are as follows Primary Al shall be Used in the manuf of Type A alloy powder, while primary or secondary Al may be used for Type B alloy powder. Type A powder shall be granular and shall contain no slivers, chips, or machine turnings... 

Chemical Composition Mg-Al alloy powder shall conform to the composition requirements shown in the following table ... 

Refs 1) US Joint Army-Navy Specification JAN-M-454 (21 Feb 1947) with Amendment 1 (15 Feb 1952), Magnesium-Aluminum Alloy, Powdered 2) N.H. Furman, Scott s Standard Methods of Chemical Analysis , 5th Ed, Vol 1, Van Nostrand, Princeton, NJ (1961), 539—53 3) US Military Specification... 

Simmonds, J. J. (1983). The miracle mixture glass-ionomer and alloy powder. Texas Dentist, October 6-12. 

Table 57.2. The Properties of the Multiphase Alloy Powders and the Resulting...

Figure 57.16. The comparison of A1 leachability for the casted single-phase alloy powders, the casted multiphase alloy block and CA53. The CA53 was activated at it with 10 wt.% NaOH and its A1 content was determined by x-ray. The other casted alloys were activated at it with 20 wt.% NaOH and their A1 contents were ascertained by SEM EDX.

The alloy powder (used in hydrogen-storage systems) may ocasionally be pyrophoric after hydriding-dehydriding operations, igniting when placed on a combustible surface (e.g. weighing paper). 

SEM of graphitic nanofiber prepared by decomposition of C2H4 H2 = 1 4 gas flow over NiCu alloy powder. (Reproduced from Xu, W.-C., Takahashi, K., Matsuo, Y., Hattori, Y., Kumagai, M., Ishiyama, S., Kanekoc, K., and Iijima, S., Int. ]. Hydrogen Energ. 32(12), 2504-2512, 2007. With permission.)... 

Numerous atomization techniques have evolved for the production of metal/alloy powders or as a step in spray forming processes. Atomization of melts may be achieved by a variety of means such as aerodynamic, hydrodynamic, mechanical, ultrasonic, electrostatic, electromagnetic, or pressure effect, or a combination of some of these effects. Some of the atomization techniques have been extensively developed and applied to commercial productions, including (a) two-fluid atomization using gas, water, or oil (i.e., gas atomization, water atomization, oil atomization), (b) vacuum atomization, and (c) rotating electrode atomization. Two-fluid atomization... 

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