ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The microstructure of a series of Ni-B alloys (15 at%〈B〈30 at%) rapidly quenched by melt spinning has been investigated by means of conventional transmission and high-resolution electron microscopy (HREM), and analysed by electron energy loss spectroscopy (EELS) adapted on a scanning transmission electron microscope. A metastable phase is observed in the composition range 21 to 28 at% B where the orthorhombic Ni3B phase (a=0.44 nm,b=0.52 nm,c=0.66 nm) is expected. High-resolution electron microscopy images of Ni-25 at% B rapidly quenched indicate that a two-phase structure is observed. A metastable phase is observed with a periodicity of 1.0 nm. HREM images and EELS analyses led us to propose the structure of this metastable phase. This phase (Ni5B2) is correlated with the monoclinic Hägg carbide Fe5C2. Depending on the velocity of the substrate and on the boron concentration, a variety of microstructures has been observed from a faulted to a semi-amorphous structure. The structures are related to the solidification behaviour and the heat flow in the undercooled melt. Particular attention was paid to the eutectic Ni-Ni3B composition.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02385752
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