ISSN:
1436-5073
Keywords:
Al alloys
;
mechanofusion
;
solid state reactions
;
intermetallic compounds
;
QC phases
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Mixtures of aluminium and other metal powders were milled in a Hosokawa AM-15F mechanofusion system in order to produce composite materials with coated or layered microstructure. These composites were then annealed or used in plasma spraying experiments. The intermetallic phases produced in the consecutive steps of the treatment were investigated by different methods. In the case of the Al-Ni powder system the presence of intermetallic phases confirmed that phase forming solid state reactions start during the first, mechanofusion step. After milling the powder mixture in the Hosokawa equipment, crystalline Al3Ni could be detected by TEM. A second intermetallic phase, Al3Ni2 was also observed after a heat treatment at 750 K. In Al-Cu-Fe and Al-Cu-Co powder composites, produced by milling, binary and ternary phases could be found only after plasma spraying. That means that in these cases the thermodynamic and kinetic requirements of the reactions could not be fulfilled by this mild milling. Nevertheless, the considerably large specific surface of the metal-metal interfaces, formed during the milling process in the ternary composites, makes it possible to produce multi-phase coatings from these composites. It means that only two technological steps are required (milling — plasma spraying). All of the other known technologies consist of three steps: alloy preparation — milling — plasma spraying or alloy preparation —atomisation — plasma spraying. Similarities and differences between the reactions taking place in thin films and thin and/or small milled particles are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01246162
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