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研究了AZ91D镁合金均匀化退火处理后等温冷却过程中β-Mg17Al12析出相的尺寸和分布均匀性,探讨等温温度和时间对β-Mg17Al12相析出行为和形态乃至合金力学性能的影响。结果表明:在420℃保温20 h后在150~300℃等温冷却2~6 h,β-Mg17Al12相以层片状形态在晶内均匀析出,随着等温冷却保温时间的延长,β-Mg17Al12相析出量增加,且其平均层片间距随等温温度升高而增大。力学性能测试结果表明:经420℃均匀化退火20 h后在250℃等温冷却保温6 h,硬度从铸态的57.7 HB增加到83.9 HB,屈服强度和抗拉强度分别提高了28%和37%,抗压强度提高了49.6%,伸长率由铸态的2%增加到6.52%。
The size and distribution uniformity of β-Mg17Al12 precipitates in AZ91D magnesium alloy during homogenization annealing were studied. The effects of isothermal temperature and time on the precipitation behavior and morphology of alloy β-Mg17Al12 and the mechanical properties of the alloys were also investigated. The results show that the β-Mg17Al12 phase precipitates in the form of lamellar morphology in the form of lamellar morphology after being isothermally cooled at 420 ℃ for 20 h and isothermally cooled at 150-300 ℃ for 2 ~ 6 h. With the isothermal cooling and holding time prolonging, the β-Mg17Al12 phase Precipitation increased, and the average layer spacing increased with isothermal temperature. The results of mechanical tests show that the hardness increases from as high as 57.7 HB to 83.9 HB after as-quenched at 420 ℃ for 20 h and isothermally cooled at 250 ℃ for 6 h, yield strength and tensile strength increase by 28% and 37% , Compressive strength increased by 49.6%, elongation increased from as-cast 2% to 6.52%.