The microstructure evolution of Al-Zn-Mg-Cu alloy was studied by differential scanning calorimetry （DSC） and transmission electron microscopy （TEM） during different rate cooling processes. Based on the DSC results, the kinetics analysis was carried out. The results indicate that the precipitation of η phase is the predominant transformation for the alloy during the cooling process after the solution treatment. And the η phase nucleates on dispersoids and at grain boundaries. The amount of η phase decreases with increasing cooling rate, and reduces by 75% as the cooling rate increases from 5 to 50 ℃/min. The kinetics of the precipitation of η phase can be described by the Kamamoto transformation model when the cooling rate is a constant.
随着强力、高效切削方式的推进以及难加工材料的加工,由切削力引起的工件加工误差(简称切削力误差,cutting force induced error)不容忽视。本文提出切削力误差直接测量法,实现了工作过程中切削力和误差数值的直接对应。通过对不同测量方法所反映机床误差特性的甄别,提出建立基于"一维"和"二维"测量技术的混合误差模型的思想,研究成果能够为数控机床动态行为对加工性能的影响机理提供试验数据和理论基础。
