-1）下的動(dòng)態(tài)拉伸試驗(yàn)；根據(jù)試驗(yàn)數(shù)據(jù)對(duì)J-C本構(gòu)模型中的應(yīng)變率強(qiáng)化項(xiàng)和熱軟化項(xiàng)進(jìn)行了修正，并標(biāo)定相關(guān)模型參數(shù)。進(jìn)一步開(kāi)展數(shù)據(jù)仿真分析，并對(duì)比試驗(yàn)與仿真的斷裂位置和真應(yīng)力-應(yīng)變曲線，驗(yàn)證失效模型參數(shù)的可靠性。使用SEM對(duì)鎂合金斷口微觀形貌進(jìn)行觀察，探究溫度、應(yīng)變率對(duì)鎂合金失效影響的微觀行為特征，鎂合金在準(zhǔn)靜態(tài)拉伸與動(dòng)態(tài)拉伸過(guò)程中斷口形貌中均發(fā)現(xiàn)了韌窩與解理臺(tái)階，為混合斷裂機(jī)制，且高應(yīng)變速率下解理臺(tái)階稍多，這與鎂合金高應(yīng)變速率下的應(yīng)變敏感性有關(guān)；而在高溫拉伸過(guò)程中表現(xiàn)為韌性斷裂。;The mechanical behavior and fracture failure characteristics of Mg-9Gd-4Y-2Zn-0.5Zr alloy at various strain rates were investigated, including parameter calibration and verification based on the Johnson-Cook (J-C) constitutive model and failure model. Quasi-static tensile tests at different temperatures were conducted by a universal testing machine, while dynamic tensile tests at high strain rates (1000–3000 s-1) were performed by a Hopkinson bar apparatus. Based on the experimental data, modifications were made to the strain rate hardening and thermal softening terms of the J-C constitutive model were modificated, and relevant model parameters were calibrated. Further numerical simulations were carried out; the fracture locations and true stress-strain curves between experimental and simulated results were compared to validate the reliability of the failure model parameters. The fracture morphology of the magnesium alloy was observed and the microstructural characteristics influencing failure under different temperatures and strain rates were explored. Both dimples and cleavage steps were observed in the fracture morphologies during quasi-static and dynamic tensile processes, indicating a mixed fracture mechanism. Slightly more cleavage steps are found at higher strain rates, which is related to the strain rate sensitivity of the magnesium alloy. In contrast, ductile fracture is predominant during high-temperature tensile tests."/>