The microstructure and formation mechanism of laser clad Ni60 Acoating were studied by meansof XRD, SEM, TEMand EDAXetc. Theresultsshow thatthe microstructureofthe coatingiscontrolled bytheratiooftemperature gradie...The microstructure and formation mechanism of laser clad Ni60 Acoating were studied by meansof XRD, SEM, TEMand EDAXetc. Theresultsshow thatthe microstructureofthe coatingiscontrolled bytheratiooftemperature gradient Gand solidification speed υ( G/υ)atthesolid liquidinterface. Attheinterfaceof molten pool/substrate, G/υisquitelarge,and Ni basedsolid solutionsgrowingintheform oflow speed planar grain boundary form abonding belt. With the advancement of the solid liquid interface, G/υdecreases, and a bonding zone mainly composed ofcomplex cellulareutecticsof Ni+ M23( CB)6 and Ni+ Ni3Bisformed when G/υisstilllargeenough. Further decrease willlead to a clad layerthat exhibitscellular and dendritic Ni basedsolidsolutions,dendriticor discontinuousnetwork M7( CB)3 and complex eutectics( Ni+ M23( CB)6 and Ni+ Ni3 B) between them .展开更多
文摘The microstructure and formation mechanism of laser clad Ni60 Acoating were studied by meansof XRD, SEM, TEMand EDAXetc. Theresultsshow thatthe microstructureofthe coatingiscontrolled bytheratiooftemperature gradient Gand solidification speed υ( G/υ)atthesolid liquidinterface. Attheinterfaceof molten pool/substrate, G/υisquitelarge,and Ni basedsolid solutionsgrowingintheform oflow speed planar grain boundary form abonding belt. With the advancement of the solid liquid interface, G/υdecreases, and a bonding zone mainly composed ofcomplex cellulareutecticsof Ni+ M23( CB)6 and Ni+ Ni3Bisformed when G/υisstilllargeenough. Further decrease willlead to a clad layerthat exhibitscellular and dendritic Ni basedsolidsolutions,dendriticor discontinuousnetwork M7( CB)3 and complex eutectics( Ni+ M23( CB)6 and Ni+ Ni3 B) between them .
