【摘 要】
:
In the present work,the microstructural characteristics and mechanical properties of Al-l.5 Mg-0.6Si and Al-3.0 Mg-0.6Si alloy containing 3 wt% Li were investigated by optical microscopy (OM),X-ray diffraction analysis (XRD),scanning electron microscopy (
【机 构】
:
State Key Laboratory of Nonferrous Metals and Processes,GRINM Group Co.,Ltd,Beijing 100088,China;GRI
论文部分内容阅读
In the present work,the microstructural characteristics and mechanical properties of Al-l.5 Mg-0.6Si and Al-3.0 Mg-0.6Si alloy containing 3 wt% Li were investigated by optical microscopy (OM),X-ray diffraction analysis (XRD),scanning electron microscopy (SEM),time of flight-secondary ion mass spectrometry (SIMS),transmission electron microscopy(TEM),and mechanical performance testing.The addition of Li reduces the density of the base alloy by up to 8.4%.The residual second phases contain Mg and Si in the hot-rolled condition,but the Mg/Si atomic ratio decreases after quenching,which means that Li substitute some of the Mg and convert Mg2Si into a (Mg,Li)2Si phase during solution treatment.The results of SIMS observations confirm this.The high Mg-containing alloy has a more rapid hardening response compared to the low Mg-containing alloy.TEM observation reveals that the δ\'-Al3Li + β\"-Mg2Si dual phases can be observed in the high Mg-containing alloy after aging for 100 h at 170 ℃.The higher Mg content enhances the precipitation of the δ\'phase,which results in the high Mg-containing alloy having a larger average diameter size of δ\'particles and wider δ\'-precipitate-free zones (δ\'-PFZs).The mechanical properties are significantly improved with the elastic modulus increasing by more than 16.5%.However,the existence of large second phases and wide δ\'-PFZs in Li-containing alloys is detrimental to their ductility;as a result,their elongation is much lower than that of the base alloy.
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