Effect Of B On Microstructure And Properties Of High Aluminum Zinc-based Alloys ZA32

Due to the shortage of copper and its increasing price, as replacement ofbronze, high aluminum zinc-based alloys developed gradually in recent years.Because of and the low price, energy saving, high quality of high aluminum zinc-based alloys, This alloy has been increasingly widely used at domestic andabroad. At present this alloy is used as replacement of bronze and brass inindustry. Resources of zinc and aluminum are particularly rich in our country.However, the major problem of applications of this alloy in industry is the lowplastic toughness. Therefore developing the excellent comprehensive propertiesof high aluminum zinc-based alloys has propound academic value andcommercial value for our country.In this paper, first the contentration of aluminum is further improved on thebasis of ZA27, and0.32%B is added. Metal mold corresponding to standardtensile samples is used. Two groups of ZA32and ZA32-0.32B samples aresolidified with the pouring temperatures of590℃. Then the two groups ofsamples experiencesolid-solution treatment at365℃with holding time3h andaging at100℃with holding time6h. Finally their frictional and wear behaviorare examined.High aluminum zinc-based alloys ZA32-0.32B are solidifed using the metalmold casting. According to eutectic reaction theory for Al-B alloy,0.32%B isadded to ZA32. At the beginning of solidification, a large of α-Al and hardceramic phase AlB2precipitate in advance. Microstructure is refined and strengthand hardness are improved. Then η phase, ε phase and ceramic phase AlB2uniformly and dispersively precipitate from the alloy matrix through solidsolution aging treatment. The performance of the alloy is improved further. Whenaging for1.5h tensile strength and hardness reach maximum, respectively435MPa and156HBS. When aging for6h expand rate reaches a maximum,7.5%. Test of sliding friction and wear performance are carried out ZA32combined with ZA32-0.32B under condition of dry friction. Experimental resultsshow that after adding B to ZA32alloy, particles of the hard ceramic phase AlB2are formed, and the organization is refined, at the same time the alloy’s hardnessand wear resistance are also improved. Analyses of the organization mechanism,organizational characteristics of high aluminum zinc-based alloys ZA32-0.32Bare that hard spots AlB2and ε phase scatter on the soft matrix. The more andeven hard points contact with the grinding material in the process of friction,which makes the alloys withstand greater force without peeling, thus the wearresistance of the alloys is improved.