摘要
Fabrication of ternary Nb-17Si-23Ti alloys was attempted by in situ reaction laser melting deposition（LMD）with dual powder feeding method from Nb-28 at.% Ti powder mixture and pure Si powder.The microstructures of the as-deposited alloys were examined with scanning electronic microscope,and the phase constituents were analyzed by X-ray energy-dispersive spectrometer and X-ray diffraction.Furthermore,the effect of laser power on microstructure charac-teristics,microhardness and indentation fracture toughness was also investigated.The in situ reaction LMD process resulted in remarkable refinement of the microstructure.The as-deposited samples mainly consisted of Nbss,metastable（NbTi）3Si and Ti-rich Nbss.With the increase in the laser power from 1000 to 2000 W,the Nbss morphology changed from discontinuous dendritic to near equiaxed,but the Ti-rich Nbss phase tended to vanish.Furthermore,with the increase in the laser power,the microhardness of as-deposited samples increased from 822 to 951 HV,while the indentation fracture toughness was improved from 12.3 to 14.1 MPa mt/2.The corresponding mechanism is also discussed.
Fabrication of ternary Nb-17Si-23Ti alloys was attempted by in situ reaction laser melting deposition（LMD）with dual powder feeding method from Nb-28 at.% Ti powder mixture and pure Si powder.The microstructures of the as-deposited alloys were examined with scanning electronic microscope,and the phase constituents were analyzed by X-ray energy-dispersive spectrometer and X-ray diffraction.Furthermore,the effect of laser power on microstructure charac-teristics,microhardness and indentation fracture toughness was also investigated.The in situ reaction LMD process resulted in remarkable refinement of the microstructure.The as-deposited samples mainly consisted of Nbss,metastable（NbTi）3Si and Ti-rich Nbss.With the increase in the laser power from 1000 to 2000 W,the Nbss morphology changed from discontinuous dendritic to near equiaxed,but the Ti-rich Nbss phase tended to vanish.Furthermore,with the increase in the laser power,the microhardness of as-deposited samples increased from 822 to 951 HV,while the indentation fracture toughness was improved from 12.3 to 14.1 MPa mt/2.The corresponding mechanism is also discussed.
基金
the support by the National Natural Science Foundation of China(Grant No.51605456)
