Effects Of Heat Treatment Process On Microstructure And Property Of Spray-deposited Magnesium Alloys Wire Containing Nd

The development of magnesium alloy welding wire is of great significance in the field of welding.And both the wire forming rate and the performance of magnesium alloy welding wire will need to be further developed and improved.In addition to the traditional strengthening methods such as grain refinement,high alloying,second phase strengthening,solid solution strengthening and so on,the long period ordered structure(or LPSO structure phase)is formed in magnesium alloy.It can not only improve the strength of magnesium alloy welding wire,but also improve the plasticity.In this paper,Mg-9Al-3Zn-6Ca-1Mn,Mg-9Al-3Zn-6Ca-1Mn-1Nd and Mg-9Al-3Zn-6Ca-1Mn-2Nd was prepared by adding Nd with different mass fraction(0,1,2%)on the basis of high alloyed magnesium alloy which prepared by spray deposition and rapid solidification.Magnesium alloy wire preextruded billet was prepared by hot extrusion deformation at 340 ? at 25:1.The microstructure changes of magnesium alloy wire pre-extruded billet with different Nd content were studied by TEM,XRD and other instruments.Then,the pre-extruded billet of magnesium alloy wire with different Nd contents is subjected to solution treatment at 200,250,300,350,400 ?,and the second phase particle size is performed by SEM,XRD,etc.And the effects of Nd content and solution temperature on the second phase particles and strength were analyzed.Finally,the calculation of the vacancy formation energy of pre-extruded blanks of different Nd content magnesium alloy welding wires was carried out by electric resistance method as well as the calculation of the stacking fault probability of 2% Nd magnesium alloy welding wire pre-extruded blanks were carried out by peak width broadening method.And analysis the effect of Nd content on vacancy formation energy and the effect of solution temperature on stacking fault probability.The experimental results show that the addition of Nd to the magnesium alloy prepared by spray deposition can form nanometer Mg-Nd-Zn 24R-LPSO structure phase on the second phase of the alloy.The second phase particles of Nd magnesium alloy wire pre-extruded billet after hot extrusion deformation can be twinned,which is beneficial to improve the strength and extensibility of magnesium alloy welding wire.The hardness of magnesium alloy wire pre-extruded billet not only increases at first and then decreases with the increase of solid solution temperature,but also increases with the increase of Nd content.With the increase of Nd content,the vacancy formation energy of magnesium alloy wire pre-extrusion blank can gradually decrease,and the 2Nd vacancy formation energy can be the lowest,which can promote the formation of the layer and LPSO.Above the experimental studies,it is found that the grain size of the pre-extruded blank containing Nd magnesium alloy wire has been significantly refined by spray deposition technology,and the strength and elongation of the billet have been promoted by the combined action of LPSO and twins in the second phase.The change of microstructure and properties of Nd magnesium alloy wire pre-extruded billet after solid solution treatment provides an important theoretical basis and guiding significance for the next step in the preparation of magnesium alloy welding wire.