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为了控制超塑性流动和断裂并研究变形能的变化,采用拉伸实验和显微组织定量方法获得Mg-7.28Li-2.19Al-0.091Y合金的应力和晶粒尺寸并建立新的高温变形能模型。结果表明,晶粒内部变形能随应变速率增大而增大,随温度升高而降低;晶界变形能的变化与晶粒内部变形能的变化相反。在给定温度下,临界空洞形核能随应变速率增大而降低,使空洞形核变得容易;在给定应变速率下,临界空洞形核能随变形温度升高而增大,导致空洞形核变得困难。新建立的临界空洞形核半径和能量模型为预测微裂纹的产生和提高成形零件的使用寿命提供了一个新途径。
In order to control the superplastic flow and fracture and to study the variation of deformation energy, the stress and grain size of Mg-7.28Li-2.19Al-0.091Y alloy were obtained by tensile test and microstructure quantitative method, and a new high temperature deformation energy model . The results show that the internal deformation of grain increases with the increase of strain rate and decreases with the increase of temperature. The variation of grain boundary deformation energy is opposite to that of grain internal deformation energy. At a given temperature, the critical void nucleation energy decreases with increasing strain rate, making void nucleation easier. At a given strain rate, the critical void nucleation energy increases with increasing deformation temperature, resulting in cavitation nucleation It becomes difficult. The newly established critical cavity nucleation radius and energy model provides a new way to predict the generation of micro-cracks and improve the service life of formed parts.