【摘要】：以Mg-17Zn-1Y合金作為本文的研究對象,采用OM、SEM、XRD和EDS等分析方法對合金的組織和物相進(jìn)行研究,探索其在不同壓力下(1GPa、2GPa以及3GPa)凝固的的合金在組織、相和力學(xué)性能等方面的變化規(guī)律,實驗得出的數(shù)據(jù)對于豐富高壓凝固理論有一定意義。實驗結(jié)果表明:均勻化處理后Mg-17Zn-1Y合金的組織中有α-Mg、14H和Mg7Zn3相,Mg7Zn3以長條狀、網(wǎng)狀分布在基體中,14H相呈現(xiàn)板條狀或?qū)悠瑺�。高壓固溶處理后的合�?固溶壓力不斷提高,14H相從板條狀、層片狀變?yōu)榧?xì)板條狀和針狀,Zn在α-Mg中的含量在常壓下為2.44at%;當(dāng)固溶壓力變?yōu)?GPa時候達(dá)到2.67at%,最后由2GPa時的2.82at%變?yōu)?GPa時的3.40at%,而隨著固溶壓力的增大,Y的含量逐漸減少,從1GPa的0.28at%變?yōu)?GPa時的0.12at%,最終減小到3GPa的0.01at%。在1GPa下凝固的合金組織中,Mg-Zn二元相和α-Mg形成共晶組織并且交錯形成網(wǎng)狀結(jié)構(gòu),14H以平行方式分布在基體中,形貌為板條狀或?qū)悠瑺?同時有部分富Y相分布在基體中。當(dāng)凝固壓力升高到2GPa時,相組成仍然為α-Mg、Mg-Zn二元相以及14H,14H相數(shù)量大大增加,同時Mg-Zn二元相體積分?jǐn)?shù)增大,部分網(wǎng)狀結(jié)構(gòu)破碎,同時仍有塊狀和點(diǎn)狀的富Y相生成。在3GPa下凝固的合金組織中14H相的含量減少,大部分網(wǎng)狀結(jié)構(gòu)消失,組織明顯細(xì)化,14H相從原來的板條狀或?qū)悠瑺钭優(yōu)榧?xì)針狀。當(dāng)凝固的壓力逐漸增大,Y在α-Mg中的固溶度減小,從1GPa下的0.37at%減小至3GPa下的0.07at%,而Zn原子的含量在常壓下為2.44at%,當(dāng)壓力升高到1GPa增加到2.58at%,隨后從2GPa下的2.76at%升高至3GPa下的3.89at%。固溶、凝固壓力對合金的力學(xué)性能也有改善,室溫的抗拉強(qiáng)度從常態(tài)凝固下的48.7MPa強(qiáng)化到3GPa下凝固的139.6MPa,維氏硬度則從1GPa時的113.1HV變?yōu)?GPa時的132.3HV,在3GPa時增大至134.2HV。
[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 偽-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 偽-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 偽-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 偽-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 偽-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.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG244;TG146.22

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