高压对Mg-17Zn-1Y合金凝固组织及力学性能的影响
[Abstract]:The microstructure and phase of Mg-17Zn-1Y alloy solidified under different pressures (1GPa, 2GPa and 3GPa) were studied by means of OM,SEM,XRD and EDS, and the microstructure of the alloy was studied by means of OM,SEM,XRD and EDS. The experimental data can be used to enrich the theory of high pressure solidification due to the variation of phase and mechanical properties. The experimental results show that there are 伪-Mg,14H and Mg7Zn3 phases in the microstructure of Mg-17Zn-1Y alloy after homogenization, and Mg7Zn3 is in the form of long strips and reticulate distribution in the matrix, and the 14H phase is lath or lamellar. After high pressure solution treatment, the solution pressure of the alloy increases continuously. The 14H phase changes from lath, lamellar to thin strip and needle, and the content of Zn in 伪-Mg is 2.44 at% under atmospheric pressure. When the solution pressure changes to 1GPa, it reaches 2.67 at%, and finally changes from 2.82 at% at 2GPa to 3.40 at% at 3GPa. With the increase of solution pressure, the content of Y decreases gradually, from 0.28 at% of 1GPa to 0.12 at% of 2GPa. It finally decreased to 0.01 at% of 3GPa. In the microstructure of alloy solidified under 1GPa, Mg-Zn binary phase and 伪-Mg form eutectic structure and interlaced to form reticulate structure. 14H is distributed in the matrix in a parallel manner, and the morphology is lath or lamellar. At the same time, some Y-rich phases are distributed in the matrix. When the solidification pressure increases to 2GPa, the phase composition is still 伪-Mg,Mg-Zn binary phase and 14H, and the quantity of 14H phase increases greatly. At the same time, the volume fraction of Mg-Zn binary phase increases and some reticular structures break up. At the same time, there are still massive and punctate Y-rich phases. In the microstructure solidified under 3GPa, the content of 14H phase decreased, most of the reticular structure disappeared, and the structure of 14H phase was obviously refined. The 14H phase changed from lath or lamellar to fine needle. When the solidification pressure increases gradually, the solid solubility of Y in 伪-Mg decreases, from 0.37 at% under 1GPa to 0.07 at% at 3GPa, while the content of Zn atom is 2.44 at% at normal pressure, and when the pressure increases to 2.58 at%, the content of Zn atom increases to 2.58 at%. It then rose from 2.76 at% under 2GPa to 3.89 at% under 3GPa. The mechanical properties of the alloy are also improved by solid solution and solidification pressure. The tensile strength at room temperature is enhanced from 48.7MPa at normal solidification to 139.6 MPA at 3GPa, and the Vickers hardness changes from 113.1HV at 1GPa to 132.3HV at 2GPa. Increase to 134.2 HV at 3GPa.
【学位授予单位】:哈尔滨工业大学
【学位级别】:硕士
【学位授予年份】:2017
【分类号】:TG244;TG146.22
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