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Experiment And Numerical Simulation Of Laser Welding For Zr45Cu48Al7 Bulk Amorphous Alloy

Posted on:2008-04-18Degree:MasterType:Thesis
Country:ChinaCandidate:L WangFull Text:PDF
GTID:2121360272967089Subject:Materials Processing Engineering
Abstract/Summary:PDF Full Text Request
It is well known that bulk metallic glasses (BMGs) possess many excellent properties such as high strength, high stiffness, improved abrasion resistance, high corrosion resistances and good soft-magnetic properties compared with crystalline alloys. So the BMGs have a wide application prospect in mechanical industry, electronic industry, chemical industry and avigation industry. The joining of the BMGs is an important aspect in engineering application of BMGs. Therefore, the investigation of the crystallization mechanics under the action of the thermal cycle makes a good sense nowadays.In this dissertation, the laser beam welding technology continued to be used to joint the BMGs Zr45Cu48Al7 under the low output power among 300~500W and the scanning velocity among 3~4m/min after some tries in high output power by some pioneers. The result showed crystallization occurred in the melt zones of all samples; and the main crystallization phase was like crassitude branches in the output of 500W and the scanning velocity of 3m/min, when the scanning velocity got to the 4m/min, which became shorter and the center crystallization phase turned up. The alloys in the bead and head-affected zone might keep amorphous when output power is 300W or 500W, and the scanning velocity is 4m/min, but crystallization occurred in the melt zone. The activation energy of BMGs had been calculated by the method of DSC and Kissinger in the continued heated and cooled processing, and that result suggested that head-affected zone was easier to crystal than the bead which agreed with the result of experiments. The key of alloys in bead which kept amorphous in the process of laser beam welding was that how to avoid the intersect of the melted -cooled cycle and T-T-T cycle, and that is related the formation ability of the liquid BMGs. The head-affected zone always kept solid in the process of laser beam welding and the main factor which deeply affected the zone lied in the cooled process, which was about the thermal stability of solid BMGs. The laser beam welding process were simulated using commercial Finite Element Method (FEM) program ANSYS. And the model of heated resource was double ellipse spheres. The dynamic temperature field and the heat cycle of the BMGs Zr45Cu48Al7 had been obtained, on the base of which the result of the weld experiment is detailed analyzed.
Keywords/Search Tags:Laser beam welding, Bulk metallic glass Zr45Cu48Al7, Numerical simulation, Crystallization behavior, Temperature field
PDF Full Text Request
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