MECHANICAL ALLOYING
MECHANICAL ALLOYING
High Energy Ball Mill Emax
Planetary Ball Mill PM 400
Alloys such as amalgama in dental medicine or stainless steel are universally known and used. The tradition- al way to produce alloys is to fuse the components at very high temperatures. If only small quantities are required or if the alloys cannot be fused by melting mechanical alloying is an alternative. For this application ball mills are ideally suited. They provide a high energy input due to the impact and friction effects which occur during grinding. The mechanical impact is also advantageous in mechanochemistry, for example, to produce chemical reactions without using solvents.
WHAT HAPPENS DURING MECHANICAL ALLOYING?
The fi rst alloys (bronze) were produced as early as 3,300 BC. Today, a huge variety of alloys exists which are characterized by optimized properties. Some components can be mixed when molten and remain dissolved in each other due to the formation of mixed crystalline structures. New properties, for example the improved hardness of the alloy, are a result of the atoms of the alloy element entering the crystal lattice of the basic element. Due to the different atom diameters, the lattice in the mixed crystals is distorted, the slip planes are disturbed and the metal becomes harder but also more brittle.
Powder mixture Grinding ball
Cross sectional view of one pow- der particle
Mechanically alloyed powder particles
Crystallites of different phases in a nanoscale (10-9
m)
Fig. 1: Principle of mechanical alloying MECHANICAL ALLOYING IN BALL MILLS
What if components cannot be alloyed by melting? If, for example, the melting temperatures differ so much that one component is already evaporated when the other is melting? In the late 1960s ferronickel alloys were fi rst produced by mechanical alloying to obtain extremely temperature-resis- tant materials. Mechanical alloying uses intensive kinetic processes to fuse the components in the form of powders (fi g. 1). The planetary ball mills and the high energy
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ball mill Emax provide the required energy input by strong impact effects. The powder particles are plastical-
ly deformed between the grinding balls and fused with each other by strong kinetic processes. The planetary ball mill PM 400 MA has a speed ratio of 1:-3 which further increases the impact effects and makes this mill ideally suited for mechan- ical alloying.
Direct contact: 866-473-8724
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