CN102489692A - Method for preparing Al-Ti-C-Gd grain refiner of magnesium alloys by utilizing ultrasonic waves - Google Patents

Abstract

The invention provides a method for preparing an Al-Ti-C-Gd grain refiner of magnesium alloys by utilizing ultrasonic waves and belongs to the technical field of metal materials. The method is characterized by comprising the following steps: putting a certain amount of pure aluminium, Mg-30%Gd master alloy and Al-Mg-Ti-C precast blocks in a graphite crucible, raising the temperature to 850-900 DEG C, preserving heat for 30-60 minutes, then stirring the mixture and skimming the slag; and cooling to 720 DEG C, applying ultrasonic waves for 120 seconds and then pouring. The prepared refiner comprises the following components by weight percent: 4-5% of titanium, 1-4% of carbon, 4-5% of gadolinium and 86-91% of aluminium. The cast structure of the Al-Ti-C-Gd grain refiner is an alpha-Al, TiC, Al4C3 and Al2Gd composite structure. The TiC and Al4C3 granules and Al-Gd intermetallic compounds are uniformly distributed in an alpha-Al substrate. The method has the following beneficial effects: by introducing the ultrasonic waves and the rare-earth element Gd, the wettability of C and Al melts is improved, the chemical reactions among Al, Ti and C are promoted and the generated Al2Gd, TiC and Al4C3 granules are uniformly distributed in the Al substrate; the operation process is simple; the production cost is low; the refinement effect on the magnesium alloys is good; and the strength and toughness of the magnesium alloys are obviously improved.

Description

A kind of ultrasonic wave prepares the method for Al-Ti-C-Gd magnesium alloy grains agent

Technical field

The invention belongs to the metal material technical field, relate to and utilize ultrasonic wave to prepare the method for Al-Ti-C-Gd magnesium alloy grains agent.

Background technology

Magnesium alloy is the minimum structural metallic materials of density in the practical applications, has high specific strength, specific stiffness, and advantages such as good casting character and machining property all are widely used in fields such as automobile, electronics, Aeronautics and Astronautics and national defence.But relative with aluminium alloy, the absolute intensity of magnesium alloy is lower, and temperature-room type plasticity is poor, is prone to produce defectives such as shrinkage porosite, pore, crackle in the process of setting.

Grain refinement technology can effectively be improved casting flaw, improves the intensity and the toughness of alloy.The Al-Ti-C intermediate alloy is the effective fining agent of aluminium alloy; People such as Han Guang are on " Transaction of NonferrousMetals Society of China "; 15 (2009) 1057-1064; Deliver document " Grain refinement ofAZ31 Magnesium alloys by new Al-Ti-C master alloy " and point out that this intermediate alloy has certain thinning effect to the AZ31 magnesium alloy, TiC in this intermediate alloy and Al ₄C ₃Particle can be used as the forming core core of nascent magnesium.But the tiny as easy as rolling off a log reunion of TiC particle size is difficult to scatter in the magnesium alloy metamorphic process in the Al-Ti-C intermediate alloy; And the wetability of C and Al is poor, in the preparation technology of routine, is difficult to reacted Al ₄C ₃, more than 2 influential effects to Al-Ti-C intermediate alloy refinement magnesium alloy very big.

Summary of the invention

The preparation method who the purpose of this invention is to provide the agent of a kind of magnesium alloy grains efficiently solves the phenomenon of particle agglomeration in the Al-Ti-C intermediate alloy, and the wetability of improving C and Al makes its generation Al that reacts ₄C ₃

Technical scheme of the present invention is:

(1) magnesium powder, aluminium powder, titanium valve and carbon dust are mixed, wherein the percentage by weight of each component (wt.%) is: magnesium 6.25%, and titanium 15%, aluminium and carbon mass ratio are 17～20.

(2) mixed powder compaction is become the Al-Ti-C prefabricated section of Φ 35mm * 10mm, pressure is 35MPa.

(3) fine aluminium ingot, Mg-30%Gd intermediate alloy and Al-Ti-C prefabricated section are placed graphite crucible; And adopt the ice crystal coverture to cover melt; Be warming up to 850 ℃-900 ℃ insulations and use graphite rod to stir after 30-60 minute, be cooled to 720 ℃ and apply that to be cast in preheat temperature after ultrasonic be in 300 ℃ of moulds; Ultrasonic power is 330W～350W, time 120s.

Each weight percentages of components of Al-Ti-C-Gd magnesium alloy grains agent that the present invention obtains is: titanium 4-5%, carbon 1-4%, gadolinium 4-5%, aluminium 86-91%.

Effect of the present invention and benefit are through introducing ultrasonic wave and rare earth element Gd, improved the wetability of C and Al melt, promoted the chemical reaction among the Al-Ti-C, making the Al of generation simultaneously ₂Gd, TiC, Al ₄C ₃Particle evenly distributes in the Al matrix.Operating procedure of the present invention is simple, and production cost is low, to the good in refining effect of magnesium alloy, and its intensity and toughness is significantly improved.

The specific embodiment

Be described in detail the specific embodiment of the present invention below in conjunction with technical scheme.

Embodiment 1:

Take by weighing raw material by following quality proportioning: the 60g aluminium powder; The 12g titanium valve; The 3g carbon dust; 5g magnesium powder.Powder is placed planetary ball mill, and ball milling 12h under the condition that vacuumizes takes out powder 20g, places steel mold and is pressed into the Al-Ti-C prefabricated section of Φ 35mm * 10mm at powder compressing machine, and totally 4, pressure is 35MPa.Fine aluminium ingot, 83g Mg-Gd intermediate alloy and the 40gAl-Ti-C prefabricated section of the about 263g of quality are placed graphite crucible, and adopt the ice crystal coverture to cover melt, use graphite rod to stir after being warming up to 850 ℃ of insulation 30min; Skim; Be cooled to 720 ℃ then and apply ultrasonic 120s ultrasonic tool heads is shifted out, skim, being cast in preheat temperature is in 300 ℃ of steel mold; Ultrasonic power is 330W, promptly obtains the Al-Ti-C-Gd intermediate alloy.

Embodiment 2:

Take by weighing raw material by following quality proportioning: the 57g aluminium powder; The 12g titanium valve; The 6g carbon dust; 5g magnesium powder.Powder is placed planetary ball mill, and ball milling 12h under the condition that vacuumizes takes out powder 20g, places steel mold and is pressed into the Al-Ti-C prefabricated section of Φ 35mm * 10mm at powder compressing machine, and totally 4, pressure is 35MPa.Fine aluminium ingot, 85g Mg-Gd intermediate alloy and the 40gAl-Ti-C prefabricated section of the about 270g of quality are placed graphite crucible, and adopt the ice crystal coverture to cover melt, use graphite rod to stir after being warming up to 850 ℃ of insulation 30min; Skim; Be cooled to 720 ℃ then and apply ultrasonic 120s ultrasonic tool heads is shifted out, skim, being cast in preheat temperature is in 300 ℃ of steel mold; Ultrasonic power is 340W, promptly obtains the Al-Ti-C-Gd intermediate alloy.

Embodiment 3:

Take by weighing raw material by following quality proportioning: the 54g aluminium powder; The 12g titanium valve; The 9g carbon dust; 5g magnesium powder.Powder is placed planetary ball mill, and ball milling 12h under the condition that vacuumizes takes out powder 20g, places steel mold and is pressed into the Al-Ti-C prefabricated section of Φ 35mm * 10mm at powder compressing machine, and totally 4, pressure is 35MPa.Fine aluminium ingot, 87g Mg-Gd intermediate alloy and the 40gAl-Ti-C prefabricated section of the about 270g of quality are placed graphite crucible, and adopt the ice crystal coverture to cover melt, use graphite rod to stir after being warming up to 850 ℃ of insulation 30min; Skim; Be cooled to 720 ℃ then and apply ultrasonic 120s ultrasonic tool heads is shifted out, skim, being cast in preheat temperature is in 300 ℃ of steel mold; Ultrasonic power is 340W, promptly obtains the Al-Ti-C-Gd intermediate alloy.

Embodiment 4:

Take by weighing raw material by following quality proportioning: the 51g aluminium powder; The 12g titanium valve; The 12g carbon dust; 5g magnesium powder.Powder is placed planetary ball mill, and ball milling 12h under the condition that vacuumizes takes out powder 20g, places steel mold and is pressed into the Al-Ti-C prefabricated section of Φ 35mm * 10mm at powder compressing machine, and totally 4, pressure is 35MPa.Fine aluminium ingot, 85g Mg-Gd intermediate alloy and the 40gAl-Ti-C prefabricated section of the about 263g of quality are placed graphite crucible, and adopt the ice crystal coverture to cover melt, use graphite rod to stir after being warming up to 850 ℃ of insulation 30min; Skim; Be cooled to 720 ℃ then and apply ultrasonic 120s ultrasonic tool heads is shifted out, skim, being cast in preheat temperature is in 300 ℃ of steel mold; Ultrasonic power is 350W, promptly obtains the Al-Ti-C-Gd intermediate alloy.

Claims (1)

1. a ultrasonic wave prepares the method for Al-Ti-C-Gd magnesium alloy grains agent, and its characteristic comprises the steps:

(1) magnesium powder, aluminium powder, titanium valve and carbon dust are mixed, wherein the percentage by weight of each component (wt.%) is: magnesium 6.25%, and titanium 15%, aluminium and carbon mass ratio are 17～20;

(2) mixed powder compaction is become the Al-Ti-C prefabricated section of Φ 35mm * 10mm, pressure is 35MPa;

(3) fine aluminium ingot, Mg-30%Gd intermediate alloy and Al-Ti-C prefabricated section are placed graphite crucible; And adopt the ice crystal coverture to cover melt; Be warming up to 850 ℃-900 ℃ insulations and use graphite rod to stir after 30-60 minute, be cooled to 720 ℃ and apply that to be cast in preheat temperature after ultrasonic be in 300 ℃ of moulds; Ultrasonic power is 330W～350W, time 120s.