The Effect Of Alloy Elements On Microstructure And Properties Of ZA27

ZA27 alloys are simple at smelting techniques and have excellent mechanical properties,machining properties and especial wearable properties;Furthermore, the sources of raw material are wide,the cost is lower and it is not contaminative. Due to these advantages,this type of alloy has developed quickly now.However, because the develop time is not long,the investigation on high aluminium Zn-based alloy has not still perfect.In this thesis,the microstructure and properties by adding different quantity elements to ZA27 is studied in the paper in virture of using measurements of Optical Microstructure(OM),X-ray Diffraction(XRD), Scan Electric Microscopy(SEM),microcosmic hardness and absorbed-in-fracture energy.The investigation result of experiments shows that:First,adding Mg and Si to the ZA27,as mass percent of Mg is 5%,abnormity block phase Mg₂Si is trifle.With the content of Mg and Si increasing,there is large-scale Mg₂Si phase that distributes uniformly in the microstructure.With the content of Mg and Si added,the hardness and impact toughness of the testing alloy improve gradually.As well as the wear resistance and stain-resistance boost with the content of Mg and Si increasing.Second,adding different content elements Mg and Sn to the ZA27,as the content of Mg is rather lower,a little granule Mg₂Sn precipitate in the structure. Along with the content of Mg and Sn increasing,the phase Mg₂Sn of structure augment by degrees.The subparticle phase Mg₂Sn in the microstructure uniformly distributes.However as the content of Sn is much higher,granular Mg₂Sn get together in the grain boundary.With the content of Sn increasing,there is an increscent trend on the hardness.However the absorbed-in-fracture energy decreases gradually from 20 J/cm² to 1.6 J/cm².Owing to different distribution of the hard phase Mg₂Sn in the microstructure,the wear resistance of the testing alloys changes from good to bad.Excessive Pb and Mg can decrease corrosion resistance property.Thirdly,adding different content elements Mg and Pb to the ZA27,as the content of Mg and Pb is rather lower,a little granule Mg₂Pb precipitate in the structure.Along with the content of Mg and Pb increasing,the phase Mg₂Pb of structure augment by degrees.The subparticle phase Mg₂Pb in the microstructure uniformly distributes.However as the content of Pb is much higher,granular Mg₂Pb congregates in the grain boundary.Adding more Mg and Pb to the testing alloys,the hardness of the alloys' is enhanced by the different extent,whereas the compact toughness decreases remarkably.The wear resistance varies worse.As the content of Pb is the same,adding Mg doesn't influence the corrosion-resistant properties too;On the contrary,the corrosion-resistant properties of testing alloys become worse.