Bulk Metallic Glasses (BMG): A competing or complementary technology to Metal Injection Moulding?
Technical Paper: PIM International, Vol.5 No.3 September 2011, pages 78-82, 1160 words
OCAS N.V., Pres. J. F. Kennedylaan 3, 9060 Zelzate, Belgium
The objective of this article is to present the technology of bulk metallic glasses, also called amorphous metals. Next to a specific structure, a BMG has a unique combination of mechanical and physical properties that can offer an added value to the parts producing industry.
Based on extensive research, OCAS has identified that BMG can complement the MIM technology and decided to conduct a market feasibility assessment to acquire further insights into the industrialization potential for certain applications of this exciting technology.
Most metals solidify into their lowest energy state structure, i.e. a crystalline lattice structure, within microseconds once they have reached a temperature below their melting point.
These crystalline lattice structures are mostly polycrystalline, with grain structures of different shape and size.
Glass can be undercooled to below its melting temperature because of its slow crystallisation kinetics. The atoms do not form a crystalline lattice but keep their amorphous distribution.
Some metal alloys have a glass-like behaviour: if the melted alloy is cooled fast enough (hyper cooling) from the liquidus temperature to below the glass transition temperature it will freeze in its amorphous state, because below this glass transition temperature (Tg) the diffusion processes are too slow to rearrange the atoms into a crystalline phase (Fig. 1)...........
Further sections of this paper include:
- BMG properties
- OCAS work on BMG’s
- Technology push: in the search for applications
- BMG versus MIM
Figures and Tables:Fig. 1 Time -Temperature diagram
Fig. 2 Amorphous alloy IP evolution
Fig. 3 Strength versus elastic limit 
Fig. 4 Industrial deployment
Fig. 5 Levitation melter (left) and samples of cast BMG R&D samples (right)
Fig. 6a XRD graph of an amorphous sample
Fig. 6b XRD graph of an amorphous sample with crystalline phase
Fig. 7a SEM picture of a fully amorphous sample
Fig. 7b SEM picture of an amorphous sample with crystalline inclusions
Fig. 8a high resolution TEM image of the matrix
Fig. 8b the corresponding electron diffraction pattern
Fig. 9 DSC curve
Fig. 10 BMG surface roughness measurement results
Table 1 Mechanical properties; the figures for BMG are based on internal laboratory tests and literature
Table 2 Technical characteristics of equipment
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