The Fe-rich intermetallic compounds in Al-17Si-2 Fe were modified via Al-Mn-Ti quasicrystal master alloy.The effect of master alloy content on the Fe-rich phase morphology was studied by scanning electron microscope(SEM)and thermodynamic calculation.Results show that the microstructure of the Al-Mn-Ti master alloy consists of binary quasicrystal matrix and ternary AlMnTi secondary phase.The evolutive tendency of Fe-rich intermetallic compounds with content of quasicrystal Al-Mn-Ti master alloy increasing can be described as follows:long needle-shapedβphase for Al-17 Si-2 Fe alloy,long plate-shaped ternaryδphase for 3 wt%master alloy addition,Chinese-script and polyhedralαphases for 4 wt%master alloy addition and finer plate-shaped quaternaryδphase with a phases for 5 wt%master alloy addition.The ultimate tensile strength of the Al-17 Si-2 Fe alloy with4 wt%master alloy addition(a mass ratio of w(Mn)/w(Fe)≈0.7)increases by 23.8%and the friction coefficient decreases from 0.45 to 0.35 compared with those of Mnfree alloy.α-Fe phases have less negative effect on the matrix compared with the long needle-shapedβphase and the plate-shapedδphase.
Jing ZhangZhou-Yi PangLing WangChi-Chi SunNing LiuHong-Mei ChenZhao-Xia ChengKe Li
Al_(2)O_(3) particles reinforced hypereutectic Al-Si composites were prepared by in situ Fe_(2)O_(3)/Al reaction system.The thermodynamic analysis and microstructure evolution were investigated by differential scanning calorimetry,optical microscope,scanning electronic microscopy and transmission electron microscope.Results show that the reaction between Fe_(2)O_(3) and Al is spontaneous which can be separated into two steps at different temperatures.The in situ Al_(2)O_(3) particles in nano size distribute on the Al matrix accompanied with long needle-shapedβFe-rich intermetallic phase.With different content of Mn addition,βphase can be modified toα-Al15(Mn,Fe)3Si2 andδ-Al4(Fe,Mn)Si2.Both tensile strength and elongation results at room temperature and 300℃reveal that the optimal Fe-rich intermetallic phase is finer Chinese-script and polyhedralαphase with a Mn/Fe mass ratio 0.5 for the composites.Both in situ Al_(2)O_(3) particles andα-Fe phases contribute to the properties improvement of the composites。
WANG YifeiZHANG JingSUN ChichiCHENG ZhaoxiaPANG ZhouyiWANG LingCHEN HongmeiLIU Ning
