ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
The devitrification of the Fe-Ni-B-Si amorphous ribbon was investigated by thedifferential scanning calorimetry (DSC) with scanning and isothermal methods. Thedevitrification of rapidly quenched ribbons is a multilevel process. On the basis of DSCinvestigations it was determined that crystallization occurs in three processes up to 700°C inthe Fe40Ni40B16Si4 alloy. In the present work the first and second steps have been discussed.The first crystallization step involves the segregation of the Fe-Ni crystalline solid solutionfrom the amorphous matrix. During the second crystallization phase, in addition to austenite,nickel silicide and two types of iron borides crystallize as well. The ribbons were relaxed at380°C for 2 hours, following the pre-annealing at different temperatures. Pre-annealing wasperformed in the DSC within the temperature range elapsing from 395°C to 420°C. The preannealingat temperatures below the first exothermal DSC peak has an effect on thecrystallization processes. After the pre-annealing the samples were investigated by DSC. TheDSC peak of the first crystallization step shifts to higher temperatures and decrease itsenthalpy. The scanning DSC measurements, applied after the isothermal pre-annealing, wereperformed in order to determine the fraction of the ribbon transformed in the primarycrystallization step. The second DSC peak shifts to lower temperatures with a maximum of4°C. The X-ray diffraction (XRD) analyses reveal that the lattice constant changes with thepre-annealing temperatures. Such observation was also supported by the circumstance that thecomposition of the Fe-Ni solid solution undergoes certain modifications
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/14/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.537-538.185.pdf
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