医用多孔Ti-10Mo合金的制备及力学性能

以元素粉末为原料添加造孔剂碳酸氢铵,采用粉末冶金模压烧结技术制备了多孔Ti-10Mo合金,探讨了烧结工艺与造孔剂含量对合金组织、孔隙特征和力学性能的影响规律。结果表明,在1300℃烧结可制备出具有典型魏氏体组织、孔隙分布均匀的多孔Ti-10Mo合金材料;随着造孔剂含量增加,合金孔隙率增加,孔径变大孔壁变薄,当造孔剂含量达到50%,孔隙结构互相贯通,孔径尺寸大幅增加;添加50%~60%造孔剂,制备Ti-10Mo合金孔隙率为62.8%~66.9%,平均孔径尺寸为485.6~545.9μm,其弹性模量为2.9~1.3 GPa,抗压屈服强度为129.2~56.1 MPa。     

孔隙尺寸对Ti-7.5Nb-4Mo-2.5Sn形状记忆多孔合金超弹性能的影响

研究了孔隙尺寸对Ti-7.5Nb-4Mo-2.5Sn形状记忆多孔合金微观组织、力学性能及超弹性能的影响。结果表明,不同孔隙尺寸的Ti-7.5Nb-4Mo-2.5Sn多孔合金均由大部分β相组成,并含有少量α和α"马氏体相。随着造孔剂尺寸的增大,多孔合金孔隙尺寸逐渐增大。孔隙尺寸的增加使合金的弹性模量、屈服强度和压缩强度逐渐下降。不同孔隙尺寸的Ti-7.5Nb-4Mo-2.5Sn多孔合金均具备超弹性能,但孔隙尺寸的增加会使合金超弹性能下降。     

Ti-13Nb-13Zr表面多孔梯度合金的制备及性能研究

利用放电等离子烧结（SPS）技术制备了中间致密、表面多孔的Ti-13Nb-13Zr梯度合金,研究了烧结温度（950~1200 ℃）对梯度合金组织演变、界面结合、表面孔隙特征、力学及体外矿化性能的影响。结果表明：随烧结温度的逐步上升,梯度合金中α-Ti相减少,β-Ti相增多,组织逐渐连续均匀分布,晶粒得到细化,中间基体与多孔层界面呈连续过渡且形成良好的冶金结合,表面多孔层孔隙率下降而平均孔径减小;梯度合金抗压强度值随烧结温度升高呈先增大后降低趋势,而弹性模量值变化不大;综合分析,烧结温度为1150 ℃时,制备的表面多孔梯度合金不仅具有良好的力学性能（抗压强度893MPa,弹性模量16GPa）,而且具有适宜的孔隙参数（孔隙率34.7%,平均孔径340.9μm）及优异的类骨磷灰石形成能力与体外矿化性能。     

粉末冶金Ti-Mo合金的显微组织及力学性能

以元素粉末为原料,采用模压烧结技术制备了Ti-(8~20)Mo合金,并探讨了烧结工艺及Mo含量对合金组织和力学性能的影响规律。结果表明,在1400~1500℃范围内可制备出高致密且组织成分均匀的Ti-Mo合金材料。合金烧结致密化所需最低温度随Mo含量升高相应提高。当Mo含量(质量分数)为8%~16%,合金为典型魏氏体组织,Mo含量提高可使合金中β相晶粒尺寸减小,α片层含量降低并逐渐细化;而Ti-20Mo合金则由单一等轴β相晶粒组成。模压烧结Ti-Mo合金力学性能优异,其弹性模量范围为59~68 GPa;在1450℃烧结制备的Ti-14Mo合金相对具有最佳的综合性能,其硬度为35.7HRC,弹性模量为62.2 GPa,抗压强度为2227 MPa,压缩率为29.1%。     

放电等离子烧结制备医用多孔锌镁合金的孔隙特征和力学行为（英文）

采用放电等离子烧结技术制备多孔Zn-Mg合金,探讨了Mg含量对多孔合金孔隙特征和力学性能的影响,并分析了多孔Zn-Mg合金的断裂失效机制。结果表明,在造孔剂(NaCl)体积分数固定前提下当Mg含量从5%增加至15%(质量分数),由于在去除造孔剂的过程中去合金化作用,孔隙率从40.3%提升至54.3%,表面开孔直径从289μm增加到384μm。力学测试结果表明,多孔Zn-Mg合金为一种弹脆性多孔材料;3种组分中多孔Zn-10Mg合金力学性能最好,其强度与弹性模量均能满足作为承受低载荷松质骨的需求。     

孔隙率对Ti-7.5Nb-4Mo-2.5Sn形状记忆多孔合金超弹性能的影响

研究了孔隙率对Ti-7.5Nb-4Mo-2.5Sn形状记忆多孔合金微观组织和力学性能的影响。结果表明,随着孔隙率的增大,孔径逐渐增大且逐步连通,合金的弹性模量、屈服强度和压缩强度逐渐下降。不同孔隙率Ti-7.5Nb-4Mo-2.5Sn多孔合金均具备超弹性能,但孔隙率的增加会使合金超弹性能下降。     

SPS烧结温度对NiTi/表面多孔Ti梯度合金组织和性能的影响

利用放电等离子烧结技术制备NiTi/表面多孔Ti梯度合金,研究不同烧结温度对梯度合金微观组织、表面孔隙特征、力学性能及体外生物活性的影响及机理。结果表明:随着烧结温度的升高,梯度合金组织由NiTi、α-Ti、Ni、Ti_2Ni、Ni_3Ti混合相逐渐转变为单一NiTi和α-Ti相,内外层界面形成良好冶金结合,表面孔隙率和平均孔径呈缓慢减小趋势;同时抗压强度值快速增大而弹性模量值变化不大;1000℃制备的梯度合金不仅具有良好的表面孔隙特征(孔隙率35.8%、平均孔径423μm)、较高的抗压强度(632 MPa)、较低的弹性模量(9 GPa)及优异的超弹性行为(超弹性恢复应变4%),而且体外生物活性显著提高。     

造孔剂法制备多孔钴基生物材料及性能

以NH4HCO3为造孔剂,采用粉末冶金烧结工艺制备出多孔钴基生物材料。并借助XRD、金相显微镜、扫描电镜和力学试验机对多孔钴的微观结构、形貌和性能进行了检测与分析。结果表明,多孔钴的孔隙特征受到NH4HCO3造孔剂粒度、形貌、含量和烧结温度的影响。在850℃烧结温度下,添加19%(质量分数)、270~380μm的NH4HCO3造孔剂,制备出的多孔钴性能最优,其相组成为单一的α-Co相,孔隙率为64.3%,密度3.18 g/cm3,孔径尺寸300~400μm,弹性模量为1.17 GPa,抗压强度60.9 MPa,与人体松质骨力学性能相匹配。     

多孔NiTi形状记忆合金的制备工艺

以NH_4HCO_3为造孔剂,利用元素粉末混合烧结法制备了多孔NiTi形状记忆合金。研究了压制压力、烧结温度和烧结时间对多孔NiTi合金孔结构的影响,并分析了其物相组成。结果表明:随压制压力的增加,平均孔径和孔隙率逐渐减小;随烧结温度提高,多孔NiTi合金的平均孔径减小、孔隙率先增加后减少,孔隙分布趋于均匀;随烧结时间延长,多孔NiTi合金的平均孔径及孔隙率先增加后减少。在造孔剂添加量50%,压制压力250 MPa,烧结温度1000℃,烧结时间6 h条件下可制备出孔结构均匀(平均孔径为314μm,孔隙率56.3%)的多孔NiTi合金,其基体相为B2(NiTi)相。     

生物医用多孔钛的力学性能及孔结构变形行为（英文）

多孔钛材料因其优良的综合性能被视为最有潜力的生物医用材料之一。考虑到生物材料在使用过程中必然受到力的作用,重点研究了多孔钛的力学性能及其孔结构变形行为。采用添加造孔剂的粉末烧结方法制备孔隙率为36%~66%、平均孔径为230μm的多孔钛。采用扫描电镜观察孔结构形貌,通过室温压缩测试检测力学性能。多孔钛的弹性模量和抗压强度分别为1.86~14.7 GPa和85.16~461.94 MPa,具力学性能与人骨的力学性能相近。建立了多孔钛的相对屈服强度和相对密度间关系,结果表明相对密度是影响多孔钛力学性能和变形的主要因素。对于低相对密度的多孔钛而言,其变形方式为孔壁的屈服、弯曲和屈曲;而对于高相对密度的多孔钛,其变形方式主要为孔壁的屈服和弯曲。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

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.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

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.     

Thermodynamics Study on the Decomposition of Chromite with KOH

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.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

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.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

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).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

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.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

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.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

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.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

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.     

电化学噪声数据处理方法概述

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。