| Magnesium alloy is a kind of green environmental protection material and gets many values day by day in the realms,such as soldier work,aviation, aerospace,cars, motorcycle, electronics and so on.But magnesium alloy has not been in large mass production up to now,it is because of proper blemish that is avoided difficultly from magnesium alloy deeply,and lots of important techniques which become obstacle of application and development of magnesium alloy need still to be solved.Therefore,it has large benefits and effects to raise ignition-proof point and extend the area of application of magnesium alloy in order to transform resource advantage into production and technique predominance.The purpose of this research is mostly check and prove the transformation of ignition-proof point and other mechanical properties when AZ91D containing a bit of RE is added a little of metal zirconium.The experiment is divided into 10 teams by the composition of magnesium alloy,which is based on how much zirconium is added into magnesium alloy containing RE by proportion.The percentage composition of Zr respectively are 0%,0.2%,0.4%,0.6%,0.8%,1.0%,1.2%,1.4%,1.6%and 1.8%.And the result of this experiment shows that it is feasible to add a little of Zr into AZ91D containing RE by 2.0% for raising its ignition-proof point.When the amount of Zr is less than 0.8%,the change of its ignition-proof point is vehement and it will become calm when the amount of Zr is more than 0.8%.So it can be concluded that there will be the maximal degree if the content of Zr is increased sequentially.The ignition-proof point of the magnesium alloy sample containing 2.0% RE is 798℃as well as the one 785℃this time.However,the ignition-proof point is raised at about 830℃between 0.8%~1.2% more steadily after adding Zr in.Then there is more or less infection on the mechanical property of test samples.Firstly,it enhances the strength of extension of the samples because of the addition of Zr,and the effect is best among the content of Zr by 0.6%~1.0%;However,it does not has much effect on impact flexibility of samples,especially it is not seen any changes around the zone when the content of Zr is less of 6%;And the degree of hardness of magnesium alloy is also raised,even the maximal value appears when the content of Zr is in 1.0%~1.4%,which is 104.1HV0.1/20.Zirconium can refine the crystal grain of magnesium alloy as nucleus of alloplasm nucleation in subcooles liquid and decrease the speed of alloy spreading in order to prevent the crystal grain growing.Accord to many professional material,Zr has the ultimate infunction of refining grain and increasing mechanical property when its content arrive in 0.6%~0.8% in many kinds of magnesium alloy.From the result of the experiment,it is discovered that Zr has obvious effect on refining grain when its content is less than 0.8% and it does not work or it can not been found clearly by contraries;Especially when its content is more than 1.4%,the metallic phase has not any changes.But some intermetallic compound transformed by Zr and some element in the magnesium alloy take part in raising ignition-proof point more or less and depress the mechanical property either.The research has completed and achieve to the expectant purpose,but also there are some problems which is worth investigating deeply.Then the date and parts of inference can be useful theoretic prove.
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