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The Formation Of Fe-based Bulk Amorphous Alloys And Preparation

Posted on:2005-08-02Degree:MasterType:Thesis
Country:ChinaCandidate:D Q ZhaoFull Text:PDF
GTID:2191360122492440Subject:Materials science
Abstract/Summary:PDF Full Text Request
In this paper, several methods were used to design a series of Fe65Ni6Zr5W4B20, Fe60Co8Zr10Mo5W2B15, Fe61Co10Zr5W4B20, Fe60Co8Zr8Mo5W2Nb2B20 alloys. These bulk amorphous alloys with maximum diameter thickness reaching to 2mm were prepared by means of copper-mold vacuum suction casting though the raw materials are of a low purity. The results from x-ray diffraction (XRD), scanning electron microscope (SEM) and differential scanning calorimeter (DSC) demonstrate that these alloys exhibit a higher glass forming ability. DSC was used to study the crystallization kinetics of Fe61Co10Zr5W4B20 and Fe60Co8Zr10Mo5W2B15 bulk amorphous alloys by Kissinger and Ozawa equations under non-isothermal conditions, respectively. The isothermal crystallization behaviors of the two bulk amorphous alloys have been also studied. Moreover, some mechanical properties of the two amorphous alloys have been analyzed. The following results have been obtained:(1) Fe65Ni6Zr5W4B20, Fe61Co10Zr5W4B20 and Fe60Co8Zr10Mo5W2B15 bulk amorphous alloys have a higher glass forming ability (GFA). The glass transition temperature (Tg), the onset temperature (Tx) of crystallization and the supercooled liquid region ( TX= Tx -Tg) are listed as below:(2) Significant kinetic effect has been found in the glass transition temperature Tg, the onset temperature Tx of crystallization and the peak temperature Tp of crystallization.(3) Apparent activation energy of crystallization of Fe61Co10Zr5W4B20 bulk amorphous alloy has been obtained with Kissinger, Ozawa and Broido equations:(4) The compressive fracture of Fe61Co10Zr5W4B2o and bulk amorphous alloys shows a feature of brittle fracture. The compressive fracture strength ( bc) will decrease abviously after annealed. bc and compression ratio ( c) ofFe61Co10Zr5W4B20 bulk amorphous alloy are listed as follows:(5) Microhardness of Fe6iCoioZr5W4B2o and Fe60CogZr10Mo5WaB15 bulk amorphous alloys are about 1207 HV and 1343 HV, repectively. Moreover, the microhardness will increase after annealed.
Keywords/Search Tags:Fe-based bulk amorphous alloy, Activation energy of crystallization, Crystallization behavior, Compressive properties.
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