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《稀有金属材料与工程》2017,(3)
研究了超声波对双辊铸轧的Mg-3%Al-1%Zn-0.8%Ce-0.3%Mn(质量分数)合金板带材组织和性能的影响。结果表明:超声波辅助镁合金的铸轧可以提高镁合金带材的强度、延伸率和极限深拉比值,在250℃镁合金带材的极限深拉比值可以达到2.16。这些镁合金力学性能和成形能力的提升是由于超声波铸轧过程中,超声波可以细化镁基体的晶粒尺寸,并同时对合金中的Mg_(17)(Al,Zn)_(12)和AlCeMn相起到变质作用。当超声波强度达到800 W时,镁基体的晶粒尺寸可以从150μm细化到30μm,而且针状的AlCeMn相可以被变质成球状,从而提高了镁合金的力学性能和成形能力。 相似文献
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本文通过模铸法制备了一种Zn-Mg-Ti中间合金,并研究分析了Zn-Mg-Ti中间合金对纯镁显微组织和力学性能的影响。研究结果表明:中间合金主要由基体及“花朵状”Zn-Mg-Ti三元相组成。Zn-Mg-Ti中间合金对纯镁的晶粒组织有显著影响,镁合金晶粒尺寸随中间合金添加量的增大先减小后增大,当中间合金添加量为8%时,镁合金晶粒尺寸最小。镁合金晶粒细化主要归因于Ti原子在固液界面前沿偏聚,造成成分过冷,抑制晶粒长大。对比Mg-6.4wt.%Zn合金和Mg-8(Mg+8wt.%Zn-Mg-Ti中间合金)合金微观组织,发现Ti元素不仅能显著细化Mg-Zn合金晶粒尺寸,而且能够促进M-8合金中的第二相固溶于基体中。挤压态合金力学性能测试结果表明镁合金力学性能随Zn-Mg-Ti中间合金添加量增加先增大后减小,当中间合金添加量为8%时,镁合金综合力学性能最佳,其抗拉强度和延伸率分别为308MPa和21.5%。 相似文献
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通过加入稀土及其他合金元素对MB2镁合金铸锭进行复合变质处理,随后在330℃下进行挤压成形,得到强度高、塑性变形性能优良的镁合金型材,并采用金相显微镜、图像分析系统及MTS-810材料测试系统等分析了变质元素对镁合金组织性能的影响.结果表明,变质处理可以使β-Mg17Al12相由原来的连续网状分布变为分散的粒状分布,并使铸态MB2镁合金的晶粒由原来的100~200μm细化到约15~35μm;挤压变形后变质的MB2镁合金晶粒进一步细化到5~10μm左右,合金的抗拉强度和伸长率分别由原来的247MPa和13%提高到312MPa和22%. 相似文献
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在Mg-Y-Zn系长周期镁合金中加入微量Mo,探究其微合金化对基体合金组织及力学性能的影响。结果表明,铸态Mg-Zn-Y-Mn-(Mo)合金显微组织由α-Mg基体相、18R LPSO相(Mg_(12)YZn)和W相(Mg_3Zn_3Y_2)三相组成。发现微量Mo能明显细化铸态合金晶粒,显著促进合金中18R LPSO相形成,抑制W相析出。当加入0.3 wt.%Mo时,合金的显微组织和力学性能达到最佳,最小晶粒尺寸达到22μm,其抗拉强度和伸长率分别达到265 MPa和13.5%。 相似文献
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定量研究了大挤压比(81:1)条件下Mg-6xZn-xY合金的微观组织和力学性能。结果表明:随着Zn、Y含量的增加,准晶相含量逐渐增加,α-Mg基体平均晶粒尺寸先减小后增大,Mg-6Zn-1Y合金中的α-Mg平均晶粒尺寸最小为2.9μm,且尺寸分布最均匀,其标准差也达到最小,为0.77μm。随着Zn、Y含量的增加,Mg-Zn-Y合金的屈服强度和抗拉强度逐渐增大,延伸率逐渐降低。相比于α-Mg基体晶粒细化,细小准晶相含量的增加对提高Mg-6xZn-xY合金强度的作用更明显。 相似文献
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Deng-Kui Zhang Guo-Qing Wang Ai-Ping Wu Ji-Guo Shan Yue Zhao Tian-Yi Zhao Dan-Yang Meng Jian-Ling Song Zhong-Ping Zhang 《金属学报(英文版)》2019,32(6):684-694
In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone. 相似文献
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After nearly two years'tense construction the first phase of industrialized base of Shenyang Research Institute of Foundry 《中国铸造》2008,5(1):63-64
After nearly two years' tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry (SRIF), located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation. 相似文献
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Z. Sun S.L. Zheng Y. Zhang 《金属学报(英文版)》2007,20(3):187-192
Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process. 相似文献
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R. González-Martínez 《金属学报(英文版)》2007,20(4):235-240
The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke. 相似文献
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The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C). 相似文献
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The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel. 相似文献
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This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before. 相似文献
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Chao Yang He-Fei Huang Massey de los Reyes Long Yan Xing-Tai Zhou Tian Xia De-Liang Zhang 《金属学报(英文版)》2015,28(7):809
Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties. 相似文献
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Lei Li Bo Xu Wei-Ping Tong Hui Zhang Chun-Yan Ban Li-Zi He Zhi-Hao Zhao Yu-Bo Zuo Qing-Feng Zhu Jian-Zhong Cui 《金属学报(英文版)》2015,28(6):725
A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed. 相似文献
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综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。 相似文献