CN109338132A

CN109338132A - A kind of rare earth wrought magnesium alloy billet preparation method

Info

Publication number: CN109338132A
Application number: CN201811112019.XA
Authority: CN
Inventors: 胡志; 殷正; 褚晨亮; 闫洪
Original assignee: Nanchang University
Current assignee: Nanchang University
Priority date: 2018-09-25
Filing date: 2018-09-25
Publication date: 2019-02-15
Anticipated expiration: 2038-09-25
Also published as: CN109338132B

Abstract

A kind of rare earth wrought magnesium alloy billet preparation method, Mg-Al-Zn alloy is put into after being melted in crucible, the small bulk Mg-20%Gd that addition is wrapped up with aluminium-foil paper is cooled to 700 DEG C, then 15 ~ 20 DEG C/s cooling after keeping the temperature 10min, solidification, the weight percent of its alloy each component: aluminium 2.0 ~ 5.0%, zinc 0.8 ~ 1.2%, gadolinium 2.0 ~ 2.5%, manganese 0.3 ~ 0.5%, remaining is magnesium；Alloy pig is put into heat-treatment furnace, in protective gas atmosphere, 595 DEG C ~ 615 DEG C 20 ~ 40min of Isothermal treatment take out water quenching.The present invention can make (Mg, the Al) of stratiform₃Gd phase transition is at graininess Al₂Gd phase significantly improves rare earth wrought magnesium alloy plasticity and ductility.Al₂Gd particle can be used as the heterogeneous nuclei of α-Mg crystal grain, make rare earth wrought magnesium alloy billet fine microstructures rounding, and plasticity is good, fully meets its thixotropic forming requirement.

Description

A kind of rare earth wrought magnesium alloy billet preparation method

Technical field

The invention belongs to the processing technology fields of alloy, non-ferrous metal.

Background technique

It is most widely used alloy that magnesium-aluminium (Mg-Al) alloy, which is in magnesium alloy, and excellent comprehensive performance has mesh total It sees, in addition containing a small amount of Mn in alloy, is conducive to the adverse effect for eliminating harmful element, improves corrosion resisting property.But the alloy Mechanical property is low, and heat resistance and plastic processing are poor.

The appearance of novel semi-solid-state shaping technique provides for the solidification of solution tradition with the obstacle that plastic forming faces new Approach, it is considered to be the material forming method of 21 century most prospect.Good semisolid non-dendritic tissue how is obtained, is half The basis of solid molding technology and key.Guan Renguo professor of Northeastern University et al. proposes waveform inclination panel vibration semisolid Forming technique；University Of Nanchang professor Yang Xiangjie proposes rotation tilted cylinder formula system dress technology；University of Science & Technology, Beijing Mao Weimin religion It awards and has developed snakelike tube passage around casting；Non-ferrous metal total institute in Beijing has developed damper cooling tube method.Semi-solid isothermal heat Processing is a kind of new method developed in recent years, can in reheating with the n on-dendritic ingot that this method prepares semi-solid-state shaping To be directly turned into n on-dendritic ingot by the ingot of as cast condition, separate procedure needed for eliminating manufacture semi solid slurry is extensive For cast magnesium alloy semi-solid blank preparation in, but this method for wrought magnesium alloy billet preparation research also in spy The rope stage.

The unique configuration of extra-nuclear electron of rare earth element, makes it that can generate special effect in the magnesium alloy, wherein rare earth member Plain Gd has a significantly rotten ability to Mg-Al alloy, and Gu Songwei of Dalian University of Technology et al. has found that rare earth Gd can be with Refine AZ31 as-cast structure.Meanwhile document [B. Pourbahari, M. Emamy, H. Mirzadeh, " Synergistic effect of Al and Gd on enhancement of mechanical properties of magnesium alloys”, Progress in Natural Science: Materials International, 27 (2017) 228- 235] it proposes, after Gd element is added, is generating Al₂Another stratiform (Mg, Al) is also created while Gd phase₃Gd phase, this layer Shape mutually not only influence wrought magnesium alloy plastic forming ability, and cause generate high stress concentrations point, for micro-crack nucleation and Its propagation provides suitable position.Therefore, (Mg, Al)₃The formation of Gd phase will lead to the decline of wrought magnesium alloy performance.

Summary of the invention

The object of the present invention is to provide a kind of rare earth wrought magnesium alloy billet preparation methods, make (Mg, the Al) of stratiform₃Gd phase transition is at graininess Al₂Gd phase, so that rare earth wrought magnesium alloy plasticity and ductility significantly improve.

The present invention is achieved by the following technical solutions.

A kind of rare earth wrought magnesium alloy billet preparation method of the present invention, it is characterised in that by Mg-Al-Zn alloy It is put into after being heated to fusing in the crucible of 740 ~ 760 DEG C of furnace temperature, is closed among the small bulk Mg-20%Gd that addition is wrapped up with aluminium-foil paper Alloy melt is cooled to 700 DEG C after ten minutes by gold, heat preservation, then cooling with the cooling velocity of 15 ~ 20 DEG C/s, is obtained after solidification Alloy pig, the weight percent of above-mentioned alloy each component are as follows: aluminium is 2.0 ~ 5.0%, and zinc is 0.8 ~ 1.2%, and gadolinium is 2.0 ~ 2.5%, manganese It is 0.3 ~ 0.5%, surplus is magnesium；Obtained alloy pig is put into heat-treatment furnace, is carried out at Isothermal Hot in protective gas atmosphere Reason, heat treatment temperature are 595 DEG C ~ 615 DEG C, soaking time 20 ~ 40 minutes, take out water quenching, and it is solid to obtain tiny spherical half State magnesium-rare earth blank.

The solution have the advantages that: wrought magnesium alloy billet is prepared using method therefor of the present invention, stratiform can be made (Mg,Al)₃Gd phase transition is at graininess Al₂Gd phase, so that rare earth wrought magnesium alloy plasticity and ductility significantly improve.Together When, Al₂Gd particle can be used as the heterogeneous nuclei of α-Mg crystal grain, make finally obtained rare earth wrought magnesium alloy billet fine microstructures Rounding, plasticity is good, fully meets the requirement of its thixotropic forming.

Detailed description of the invention

Fig. 1 is the optical microstructure of the alloy pig prepared under the conditions of embodiment 2.

Fig. 2 is the SEM microscopic structure of the alloy pig prepared under the conditions of embodiment 2.

Fig. 3 is the optical microstructure of the wrought magnesium alloy billet prepared under the conditions of embodiment 2

Fig. 4 is the SEM microscopic structure of the wrought magnesium alloy billet prepared under the conditions of embodiment 2.

Specific embodiment

The present invention will be described further by following embodiment.

Embodiment 1: Mg-Al-Zn alloy, (mass percent of Al is the quality percentage of 2%, Zn first in the present embodiment Than being 0.8%, surplus Mg) heat is to 740 DEG C, after alloy all fusing, small bulk Mg-20%Gd that addition is wrapped up with aluminium-foil paper Intermediate alloy, it is 2.0% that wherein rare earth Gd, which accounts for the mass fraction of melt, and alloy melt is cooled to 700 after ten minutes by heat preservation DEG C, it is then cooling with 15 DEG C of cooling velocity, alloy pig is obtained after solidification；Obtained alloy pig is subjected to Isothermal treatment, etc. Warming treatment temperature is 595 DEG C, and soaking time is 40 minutes, takes out water quenching, magnesium-rare earth semi-solid blank can be obtained.

Embodiment 2: Mg-Al-Zn alloy, (mass percent of Al is the quality percentage of 3%, Zn first in the present embodiment Than being 1%, surplus Mg) heat is to 750 DEG C, after alloy all fusing, in the small bulk Mg-20%Gd that addition is wrapped up with aluminium-foil paper Between alloy, wherein rare earth Gd account for melt mass fraction be 2.0%, heat preservation alloy melt is cooled to 700 after ten minutes DEG C, it is then cooling with 20 DEG C of cooling velocity, alloy pig is obtained after solidification；Obtained alloy pig is subjected to Isothermal treatment, etc. Warming treatment temperature is 605 DEG C, and soaking time is 30 minutes, takes out water quenching, magnesium-rare earth semi-solid blank can be obtained.

Embodiment 3: Mg-Al-Zn alloy, (mass percent of Al is the quality percentage of 4%, Zn first in the present embodiment Than being 1.2%, surplus Mg) heat is to 760 DEG C, after alloy all fusing, small bulk Mg-20%Gd that addition is wrapped up with aluminium-foil paper Intermediate alloy, it is 2.5% that wherein rare earth Gd, which accounts for the mass fraction of melt, and alloy melt is cooled to 700 after ten minutes by heat preservation DEG C, it is then cooling with 15 DEG C of cooling velocity, alloy pig is obtained after solidification；Obtained alloy pig is subjected to Isothermal treatment, etc. Warming treatment temperature is 605 DEG C, and soaking time is 30 minutes, takes out water quenching, magnesium-rare earth semi-solid blank can be obtained.

Embodiment 4: Mg-Al-Zn alloy, (mass percent of Al is the quality percentage of 5%, Zn first in the present embodiment Than being 1%, surplus Mg) heat is to 750 DEG C, after alloy all fusing, in the small bulk Mg-20%Gd that addition is wrapped up with aluminium-foil paper Between alloy, wherein rare earth Gd account for melt mass fraction be 2.5%, heat preservation alloy melt is cooled to 700 after ten minutes DEG C, it is then cooling with 20 DEG C of cooling velocity, alloy pig is obtained after solidification；Obtained alloy pig is subjected to Isothermal treatment, etc. Warming treatment temperature is 615 DEG C, and soaking time is 20 minutes, takes out water quenching, magnesium-rare earth semi-solid blank can be obtained.

It is sampled by alloy pig made from embodiment 2 and by the wrought magnesium alloy billet of Isothermal treatment, is polished, thrown Alloy microscopic structure is observed under an optical microscope after light, corrosion, as shown in attached drawing 1 and attached drawing 3.It will be closed made from embodiment 2 Ingot and the wrought magnesium alloy billet for passing through Isothermal treatment are sampled observes rare-earth phase distribution situation in alloy under scanning electron microscope, As shown in attached drawing 2 and attached drawing 4.It can be seen in the drawings that isothermal heat treatment process can make (Mg, the Al) of stratiform₃Gd turns Become graininess Al₂Gd.Meanwhile part Al₂Heterogeneous nuclei of the Gd particle as α-Mg crystal grain, remaining Al₂Gd distribution of particles is equal It is even, make finally obtained rare earth wrought magnesium alloy billet fine microstructures rounding, plasticity is good, fully meets wanting for its thixotropic forming It asks.

Claims

1. a kind of rare earth wrought magnesium alloy billet preparation method, it is characterised in that Mg-Al-Zn alloy is put into 740 ~ 760 DEG C After being heated to fusing in the crucible of furnace temperature, the small bulk Mg-20%Gd intermediate alloy that addition is wrapped up with aluminium-foil paper keeps the temperature 10 minutes Alloy melt is cooled to 700 DEG C afterwards, it is then cooling with the cooling velocity of 15 ~ 20 DEG C/s, alloy pig, above-mentioned conjunction are obtained after solidification The weight percent of golden each component are as follows: aluminium is 2.0 ~ 5.0%, and zinc is 0.8 ~ 1.2%, and gadolinium is 2.0 ~ 2.5%, and manganese is 0.3 ~ 0.5%, remaining Amount is magnesium；Obtained alloy pig is put into heat-treatment furnace, Isothermal treatment, Isothermal treatment temperature are carried out in protective gas atmosphere Degree is 595 DEG C ~ 615 DEG C, soaking time 20 ~ 40 minutes, takes out water quenching, obtains tiny spherical semisolid magnesium-rare earth base Material.