Preparation And Interface Study Of Ni-Based Amorphous Fiber Reinforced Magnesium Matrix Composites

In this paper,the preparation and interface of Ni-based amorphous fiber reinforced magnesium matrix composites are investigated.Ni_60.96Nb_19.26Ta_19.78 amorphous fibers satisfying the mechanical properties were prepared.The effects of different process parameters on the infiltration quality of Ni-based amorphous fiber reinforced magnesium matrix composites were analyzed.The process parameters were optimized and Ni-based amorphous fiber reinforced magnesium matrix composites were prepared.By means of scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,energy dispersive spectrometer?EDS?,X-ray diffraction?XRD?and electronic universal testing machine.The microstructure and mechanical properties of magnesium matrix composites were studied.The mechanisms of the effect of interface bonding state on the mechanical properties of magnesium matrix composites were analyzed.Ni_60.96Nb_19.26Ta_19.78 fibers were prepared by vacuum arc melting and melt pulling method.The Characterization of these fibers using SEM,TEM,XRD,DSC and universal testing machine was conducted.The results indicate that these prepared Ni_60.96Nb_19.26Ta_19.78 fibers are amorphous with a diameter of about 50?m,high cross-section roundness,smooth surface and no obvious Rayleigh waves and grooves.The glass transition temperature Tg=661?and initial crystallization temperature T_X1=704?and super cooled liquid region"?Tx"=43?The average breaking strength and elongation of the Ni_60.96Nb_19.26Ta_19.78 fiber were 2894.96 MPa and 1.68%,respectively.Ni-based amorphous fiber reinforced magnesium matrix composites were prepared by pressing casting method with self-designed equipment.The effects of different processing parameters on the density of Ni-based amorphous fiber reinforced magnesium matrix composites were investigated.The results show that the density of Ni-based amorphous fiber reinforced magnesium matrix composites increases with the prolongation of holding time,the increase in melt temperature and the decrease in the difference between melt temperature and preheating temperature of amorphous fibers under different processing parameters.Among them,holding time is the most important for improving the density of the composites prepared,then the melt temperature,followed by preheating temperature.The optimum parameters for preparing Ni-based amorphous fiber reinforced magnesium matrix composites were obtained as follows:melt temperature T₁=680?,preheating temperature T₂=680?,holding time t=10 min.The interface bonding states between Ni-based amorphous fibers and magnesium matrix were analyzed by SEM and TEM.The interfacial bonding state between Ni-based amorphous fibers and magnesium matrix is affected by melt temperature.At moderate temperature,the thickness of interfacial reaction layer between Ni-based amorphous fibers and magnesium alloy matrix is about 4?m,a diffusion layer formed at the edge of the fibers is about 2?m,and a small amount of Mg/Ni compounds are formed in the diffusion layer.The Ni-based amorphous fibers remain amorphous.When the temperature is too high,the interfacial reaction layer of Al/Ni compound with a thickness of about 15?m appears,a diffusion layer with a thickness of 4?m is formed at the edge of the fiber,and a small amount of Mg/Ni compound is formed in the diffusion layer.The Ni-based amorphous fibers are partially crystallized.The mechanical properties of magnesium matrix composites were analyzed by electronic universal testing machine.The tensile strength of Mg-based composites increased by 76%from 129 MPa to 227 MPa after adding 4 vol%Ni-based amorphous fibers at melt pouring temperature of 680?.The tensile strength of Mg-based composites increased by 48.5%from 134 MPa to 199 MPa after adding 4 vol%Ni-based amorphous fibers at melt pouring temperature of 700?.The appropriate temperature and interfacial bonding strength resulted in the crack initiation of Mg-based composites at loading time.The stress concentration can be relaxed due to interfacial debonding and plastic deformation of magnesium matrix,which can hinder the crack propagation,and the fracture surface shows interfacial debonding and fiber pull-out phenomenon.Thus,the reinforcing effect of Ni-based amorphous fibers is brought into full play,and the tensile strength of Mg-based composites are improved.When the temperature is too high,the interfacial reactants increase and the fibers crystallize,which reduces the properties of Ni-based amorphous fiber reinforced magnesium matrix composites.