基于SPS法镁和镁合金TAZ811制备及组织性能研究
发布时间：2019-03-20 13:00
【摘要】：Mg-8Sn系合金以耐腐蚀性优异、强度高等优点而逐渐成为镁合金领域的研究热点。目前大多数学者采用铸造法制备Mg-8Sn系合金并进行研究,而主要强化相Mg2Sn偏析严重、易粗化等问题导致镁合金的塑性降低。针对此问题,本文提出了采用粉末冶金方法中的放电等离子烧结(SPS)法制备Mg-8Sn系合金,以期提高强化相Mg2Sn分布的均匀性且保证晶粒不粗化。按TAZ811配比对镁粉末、锡粉末、锌粉末和铝粉末进行高能球磨混粉,制得TAZ811合金粉末;采用SPS法制备不同烧结温度(530℃、550℃、570℃、590℃)的镁和镁合金TAZ811。采用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对其微观组织和物相进行观察;探究SPS的烧结机理;利用万能拉伸试验机对其宏观力学性能进行测试,并利用纳米压痕仪对其微区力学性能进行研究;采用电化学腐蚀试验对其耐腐蚀性进行测试。对比分析镁和镁合金TAZ811的界面行为并探讨力学性能和耐腐蚀性差异的原因。高能球磨后的各组元粉末混合均匀,从而保证了析出相沿颗粒边界分布均匀;SPS烧结过程升温速度快、保温时间短,颗粒尖端放电产生了局部高温,可实现颗粒间的有效结合且晶粒不易长大。不同烧结温度的镁和镁合金TAZ811材料,组织结合较为良好,致密度可达98%以上。微观组织观察表明:镁材料是由α-Mg相和颗粒界面处的MgO相组成;镁合金TAZ811材料主要是由α-Mg相和颗粒界面处的析出相Mg2Sn相组成,Mg2Sn的厚度在1.4μm~3.6μm之间。宏观力学性能表明:镁材料的弯曲强度随着烧结温度的升高而增强,当烧结温度为590℃时,弯曲强度最高可达136 MPa;而TAZ811材料的弯曲强度随着烧结温度的升高先增加后降低,当烧结温度为570℃时弯曲强度最高,可达215 MPa。微观力学性能表明:镁材料的颗粒界面处和颗粒中央的硬度与弹性模量随烧结温度的升高而增大,界面处性能均比颗粒中央高,在590℃时颗粒界面处硬度最高,可达0.899 GPa,颗粒中央硬度最高达0.693 GPa;与之相应,模量最大值分别为39.538 GPa和36.879 GPa。TAZ811材料的颗粒界面析出相处和颗粒中央的硬度与模量随着烧结温度的升高而增大,到590℃时有所降低。在570℃时析出相附近的硬度最高,可达1.809 GPa,颗粒中央硬度最高达1.253 GPa;与之相应,模量最大值分别为59.433 GPa和48.249 GPa。电化学试验表明:镁和镁合金TAZ811材料的腐蚀形貌为颗粒边界严重腐蚀,颗粒内部有点蚀。随着烧结温度的升高,镁材料的耐腐蚀性增强,在590℃时耐腐蚀性最好,此时腐蚀电流为2.9632×10-5 A/cm2,腐蚀电位为-1.5593 V。随着烧结温度的升高,镁合金TAZ811材料的耐腐蚀性先减弱后增强,在590℃时耐腐蚀性最好,此时腐蚀电流为1.9632×10-5 A/cm2,腐蚀电位为-1.5218 V。
[Abstract]:Because of its excellent corrosion resistance and high strength, Mg-8Sn alloys have gradually become a hot spot in the field of magnesium alloys. At present, most scholars used casting method to prepare Mg-8Sn alloys and carried on the research, but the main strengthening phase Mg2Sn segregation is serious, easy to coarsening and so on, which leads to the decrease of the plasticity of magnesium alloys. In order to improve the uniformity of the Mg2Sn distribution of the strengthened phase and to ensure that the grain is not coarsened, the Mg-8Sn alloy was prepared by spark plasma sintering (SPS) in powder metallurgy. Magnesium and magnesium alloys TAZ811. with different sintering temperatures (530C, 550C, 570C, 590C) were prepared by high-energy ball milling of magnesium powder, tin powder, zinc powder and aluminum powder according to the ratio of TAZ811, and SPS method was used to prepare magnesium and magnesium alloy TAZ811. with different sintering temperature (530C, 550C, 570C, 590C). The microstructure and phase of SPS were observed by X-ray diffractometer (XRD) and scanning electron microscope (SEM). The macro-mechanical properties were tested by universal tensile testing machine, and the micro-mechanical properties were studied by nano-indentation instrument, and the corrosion resistance was tested by electrochemical corrosion test. The interfacial behavior of magnesium and magnesium alloy TAZ811 was analyzed and the reasons for the difference of mechanical properties and corrosion resistance were discussed. The powder of each component after high energy ball milling is uniformly mixed so that the precipitated phase is uniformly distributed along the boundary of the particles. During the sintering process of SPS, the heating rate is fast, the holding time is short, the discharge at the tip of the particle produces local high temperature, and the effective bonding between the particles can be realized and the grain size is not easy to grow. The microstructure of magnesium and magnesium alloy TAZ811 with different sintering temperature is better and the densification is more than 98%. The microstructure observation shows that the magnesium material is composed of 伪-Mg phase and MgO phase at the grain interface, and the magnesium alloy TAZ811 material is mainly composed of 伪-Mg phase and precipitated phase Mg2Sn phase at the grain interface, and the thickness of Mg2Sn is between 1.4 渭 m ~ 3.6 渭 m. The macroscopic mechanical properties show that the bending strength of magnesium materials increases with the increase of sintering temperature. When the sintering temperature is 590C, the maximum bending strength can reach 136 MPa;. The bending strength of TAZ811 increases at first and then decreases with the increase of sintering temperature. When the sintering temperature is 570C, the bending strength is the highest, up to 215MPa.. The micromechanical properties show that the hardness and elastic modulus at the interface and the center of the particles increase with the increase of sintering temperature, and the properties at the interface are higher than those at the center of the particles. At 590C, the hardness at the interface is the highest (up to 0.899 GPa,). Particle center hardness up to 0.693 GPa; Accordingly, the maximum modulus is 39.538 GPa and 36.879 GPa.TAZ811, respectively, and the hardness and modulus in the center of the particles increase with the increase of sintering temperature, and decrease at 590 鈩，
本文编号：2444237
[Abstract]:Because of its excellent corrosion resistance and high strength, Mg-8Sn alloys have gradually become a hot spot in the field of magnesium alloys. At present, most scholars used casting method to prepare Mg-8Sn alloys and carried on the research, but the main strengthening phase Mg2Sn segregation is serious, easy to coarsening and so on, which leads to the decrease of the plasticity of magnesium alloys. In order to improve the uniformity of the Mg2Sn distribution of the strengthened phase and to ensure that the grain is not coarsened, the Mg-8Sn alloy was prepared by spark plasma sintering (SPS) in powder metallurgy. Magnesium and magnesium alloys TAZ811. with different sintering temperatures (530C, 550C, 570C, 590C) were prepared by high-energy ball milling of magnesium powder, tin powder, zinc powder and aluminum powder according to the ratio of TAZ811, and SPS method was used to prepare magnesium and magnesium alloy TAZ811. with different sintering temperature (530C, 550C, 570C, 590C). The microstructure and phase of SPS were observed by X-ray diffractometer (XRD) and scanning electron microscope (SEM). The macro-mechanical properties were tested by universal tensile testing machine, and the micro-mechanical properties were studied by nano-indentation instrument, and the corrosion resistance was tested by electrochemical corrosion test. The interfacial behavior of magnesium and magnesium alloy TAZ811 was analyzed and the reasons for the difference of mechanical properties and corrosion resistance were discussed. The powder of each component after high energy ball milling is uniformly mixed so that the precipitated phase is uniformly distributed along the boundary of the particles. During the sintering process of SPS, the heating rate is fast, the holding time is short, the discharge at the tip of the particle produces local high temperature, and the effective bonding between the particles can be realized and the grain size is not easy to grow. The microstructure of magnesium and magnesium alloy TAZ811 with different sintering temperature is better and the densification is more than 98%. The microstructure observation shows that the magnesium material is composed of 伪-Mg phase and MgO phase at the grain interface, and the magnesium alloy TAZ811 material is mainly composed of 伪-Mg phase and precipitated phase Mg2Sn phase at the grain interface, and the thickness of Mg2Sn is between 1.4 渭 m ~ 3.6 渭 m. The macroscopic mechanical properties show that the bending strength of magnesium materials increases with the increase of sintering temperature. When the sintering temperature is 590C, the maximum bending strength can reach 136 MPa;. The bending strength of TAZ811 increases at first and then decreases with the increase of sintering temperature. When the sintering temperature is 570C, the bending strength is the highest, up to 215MPa.. The micromechanical properties show that the hardness and elastic modulus at the interface and the center of the particles increase with the increase of sintering temperature, and the properties at the interface are higher than those at the center of the particles. At 590C, the hardness at the interface is the highest (up to 0.899 GPa,). Particle center hardness up to 0.693 GPa; Accordingly, the maximum modulus is 39.538 GPa and 36.879 GPa.TAZ811, respectively, and the hardness and modulus in the center of the particles increase with the increase of sintering temperature, and decrease at 590 鈩，
本文编号：2444237
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