电场辅助镁锂合金超塑变形行为及其在微型热管成形中的应用

LZ91 Mg-Li alloys with different grain sizes were prepared by equal channel angular extrusion process. When the extrusion passes exceeded 8 passes, the grain size was basically no longer refined. In order to investigate the superplastic deformation behavior of LZ91 Mg-Li alloy under the action of electric field, an electric field assisted superplastic uniaxial tensile experiment platform was designed and manufactured. A “decreasing” constant voltage electrification scheme was proposed, and electric field assisted uniaxial tensile experiments were carried out under different voltages, initial strain rates and grain sizes. The experimental results show that as the voltage increases, the Joule heating effect of the current increases, and the true stress-true strain curves of LZ91 Mg-Li alloy gradually present steady state rheological characteristic. The difference in elongation of initial Mg-Li alloy at all voltages is not obvious, with the maximum difference of only 16%. Compared with low voltage, the effect of initial strain rate on the superplastic deformation behavior of LZ91 Mg-Li alloy is more significant at high voltage. The electric field has a great influence on the superplastic deformation behavior of the fine-grained LZ91 Mg-Li alloy, which is mainly reflected in reducing the superplastic deformation temperature and increasing the elongation. On the basis of obtaining the superplastic properties of LZ91 Mg-Li alloy under the action of electric field, the extrusion forming process of LZ91 Mg-Li alloy micro heat pipe was designed and simulated by DEFORM-3D simulation software. The length of the micro heat pipe obtained by simulating the billet with length of 5 mm is 40 mm, the microghole depth is 0. 25 mm, and the effective strain distribution is uniform, which provides beneficial exploration for electric field assisted forming process of micro heat pipe.