Nb对富钛TiNiAl金属间化合物强化机制的影响

 采用力学压缩试验、扫描电镜和X射线衍射方法研究了Nb元素对于Ti₅₀Ni₄₂Al₈合金的力学性能和微观组织结构的影响。结果表明，Nb能够显著提高合金从室温到700 ℃之间的强度。在600 ℃时，Ti₅₀Ni₄₀Al₈Nb₂合金的压缩屈服强度和比强度分别为1 237 MPa和216 MPa/(g·cm^-3)，超过Rene95高温合金。微观组织观察及成分分析表明，Nb元素在基体和强化相Ti₂Ni（Al）中固溶，促进强化相的弥散析出和细化，并导致高强富Nb相的析出，从而提高了合金的强度。     

2195铝锂合金氩弧焊接头组织分析及力学性能研究

针对T8态2195铝锂合金在氩弧焊焊时接头裂纹敏感性高、接头力学性能差等问题,开展2195铝锂合金焊丝研制工作,对接头的显微组织、抗裂性能及综合力学性能进行了研究。结果表明,2195铝锂合金熔焊接头主要由α-Al、Al₂Cu、Al₃（Ti,Zr）相组成,具备优异的抗裂性及力学性能,其裂纹敏感性K₁＜1%,K₂=0%,接头常温抗拉强度约为390 MPa,延伸率为6.3%。BJ-4505焊丝的研制为2195铝锂合金工程应用提供技术支撑。     

双损耗Al2O3基多孔吸波材料的制备及其吸波性能

基于片状Al₂O₃陶瓷互锁结构强度高的特点,制备出夹杂石墨的高气孔率的Al₂O₃多孔陶瓷,并通过原位还原在多孔骨架中制备出Ni微粒,形成一种轻质的双损耗陶瓷基吸波材料。通过XRD、FE-SEM和EDS研究了还原温度对多孔吸波材料的组成、微观形貌、元素分布和吸波性能的影响。结果表明,还原温度升温至700 ℃可将多孔网络中Ni完全还原,形成以堆叠互锁Al₂O₃为基,夹杂片状石墨和孔表面覆盖Ni微粒的双损耗轻质吸波材料。当复合材料厚度为6.5 mm时,最小反射损耗为-35.01 dB,有效吸收带宽达到1.75 GHz。片状Al₂O₃锁定的石墨片构筑的导电网络,Ni微粒与基体之间的极化效应等共同促进复合材料良好的微波吸收性能。     

复合涂层刀具钻削高温合金Inconel 718钻削性能研究

高温合金Inconel 718是一种典型的难加工材料,本文利用DEFORM-3D软件对无涂层、TiC单涂层和TiC/Al₂O₃复合涂层硬质合金刀具进行钻削高温合金Inconel 718的仿真分析,研究在不同钻削条件下复合涂层刀具的切削性能,并进行钻削实验进行验证。结果表明：TiC/Al₂O₃复合涂层刀具能有效降低钻削轴向力和钻削温度,其轴向力降低幅度最高为20%,钻削温度最高降低了35%。通过钻削实验验证了仿真模型的准确性,可为实际钻削加工高温镍基合金Inconel 718中选择涂层种类及钻削参数提供参考。     

热处理对8090铝锂合金机械性能与显微组织的影响

 本文考查了一种Al-Li-Cu-Mg-Zr合金经不同沉淀强化工艺后的机械性能、使用透射电镜、扫描电镜考查了不同制度对应的显微组织特征。指出:控制时效温度、时间与预延展变形,可以调整δ′（Al₃Li）、S′（Al₂CuMg）相的复合沉淀得到优化组合,明显改善合金的强度与塑性。     

M50钢表面磁控溅射Ti-GLC薄膜高温摩擦学性能

为了研究高温环境下轴承钢基体上Ti掺杂类石墨碳基薄膜的实际应用，采用非平衡磁控溅射技术在M50钢表面制备Ti-GLC膜，分别在不同温度、不同线速度下与Al₂O₃陶瓷球进行摩擦磨损试验，研究其高温摩擦学性能及磨损机理。结果表明，随着温度的升高，Ti-GLC膜中的sp²键含量逐渐增大，石墨化程度加重，硬度和弹性模量逐渐降低，膜基结合力也有所降低。在室温～200℃，所制备的Ti-GLC薄膜保持优异的低摩擦与耐磨损性能，为Ti-GLC薄膜的最佳服役温度区域。在200 mm/s下，随着温度的升高，磨损形式由轻微的黏着磨损和磨粒磨损逐渐转变为严重的磨粒磨损和氧化磨损。     

TiNiPd高温形状记忆合金相变温度与相变滞后的研究

回顾了在 Ti Ni二元系合金基础上发展起来的 Ti Ni-X三元系高温形状记忆合金及 Ni Al系高温形状记忆合金。重点研究了 Ti Ni Pd系合金成分、相变温度和相变滞后的关系。结果表明 :当 Pd的原子百分数大于3 3 %,相变点的增加尤为显著,Pd的原子百分数提高 1 %,将导致合金的相变温度升高 2 0℃,当 Pd的原子百分数为 4 0 %时,Ms点可达 3 79.8℃。温度滞后ΔT随 Pd含量的增加基本不变,只是在 Pd原子百分数达到4 0 %时ΔT略有增加。相变热ΔH随 Pd含量增大呈线性增加,非常明显     

Li含量对Mg-6Y-3Zn-xLi合金微观组织和力学性能的影响

采用氩气保护真空熔炼的方法制备了铸态Mg-6Y-3Zn-xLi（x=0,5,8,11,wt%）合金,并对其进行了均匀化处理和热挤压变形。通过OM、SEM以及拉伸试验等手段研究了Li含量对合金微观组织与力学性能的影响。结果表明：随着Li含量的增加,铸态Mg-6Y-3Zn-xLi合金基体由α单相结构逐渐转变为（α+β）双相结构,晶粒尺寸和共晶化合物的形貌及分布规律也发生明显变化。均匀化处理后Mg-6Y-3Zn-xLi合金中形成的块状长周期有序（LPSO）结构相,随Li含量的增加其体积分数逐渐降低,（Mg,Zn）₂₄Y₅相数量则逐渐增多。Mg-6Y-3Zn-8Li合金进过均匀化处理和热挤压变形后表现出最优的综合力学性能,抗拉强度和延伸率分别达到278 MPa和11.6%,这主要是由于均匀分布的被破碎细化的块状LPSO相和大量细小动态再结晶的共同强化作用。     

Al含量对一种新型高W，Mo的Ni3Al基合金组织和性能的影响

为满足1050℃使用的等温锻模具材料的需求,在IC6合金成分的基础上研制了一种新型的高W,Mo强化的Ni3Al基等轴晶合金,尝试在合金中添加了不同含量的铝改善合金的抗氧化性能,并研究了铝对合金微观组织和1050℃拉伸性能和1100℃持久性能的影响.采用带能谱的扫描电镜分析了合金微观组织以及氧化膜形貌,采用X射线衍射分析了合金氧化膜的相组成.研究结果显示,随铝含量从7wt%增加到8wt%,合金的氧化增重速率明显降低,氧化皮脱落量减少,合金的抗氧化性能明显提高.力学性能测试结果表明,铝含量为7.5wt%的合金具有较好的综合高温性能,当铝含量提高到8wt%时,合金中的初生γ＇相大量增加,合金高温强度明显降低.     

浆料浸渍工艺制备高性能Al2O3/Al2O3陶瓷基复合材料

为了利于大型构件的制备,采用浆料浸渍工艺,以Nextel 720连续氧化铝纤维增韧,通过一次烧结过程制备了Al₂O₃/Al₂O₃陶瓷基复合材料。测试了复合材料的物理及力学性能,并采用光学显微镜、SEM对试样的微观形貌进行了表征。结果表明：复合材料的体积密度为2.64 g/cm³,显气孔率为26%,材料基体呈现典型的多孔结构特征;室温及1 200 ℃,复合材料厚度方向的热导率分别为3.49及2.04 W/（m·K）;200～1 200 ℃,复合材料面内方向的热膨胀系数为（4.7～7.1）×10^-6/K;复合材料室温、1 100及1 200 ℃拉伸强度分别为202.4、222.4及228.4 MPa,试样断面纤维拔出明显;室温弯曲强度为200.5 MPa,试样发生韧性断裂;层剪强度为21.0 MPa。制备的材料主要性能与美国ATK-COI陶瓷公司的同类型材料相当,部分力学性能更优异。     

热轧对Ti50Ni50-xAlx(x=1,2,4)形状记忆合金微观组织、相变和力学性能的影响

形状记忆合金的相变和力学性能受机械加工过程影响明显.在850℃下将Ti50Ni50-xAIx(x=1,2,4)形状记忆合金轧制成为板材.采用扫描电镜、透射电镜和X射线衍射对合金的微观结构研究表明:合金由NiTi相和Ti2Ni相组成,Al元素在Ti2Ni相中的固溶度比在TiNi相中高.差示扫描量热分析和电阻-温度测试表明...     

NiTiAl Intermetallic Alloys Strengthened by Mo Replacement

 NiTiAl based alloys have attracted attention as potential high temperature structural materials. Alloying is an effective way to improve their mechanical properties. The microstructures and mechanical properties of Ni₅₀Ti_44-xAl₆Mo_x (x = 0, 0.5, 1, 1.5, 3) alloys have been investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron mi-croscope (TEM) and compressive tests. It is found that Ni₅₀Ti_44-xAl₆Mo_x alloy is composed of NiTi (B2) and Ti₂Ni (FCC) phases when Mo content is no more than 1 at%. The effect of Mo solid solution hardening at room temperature has been indi-cated by the rise of yield strength and the fall of plasticity with increasing Mo content. For Ni₅₀Ti_42.5Al₆Mo_1.5 and Ni₅₀Ti₄₁Al₆Mo₃ alloys, a Mo solid solution appears and increases the yield strength by precipitation strengthening. The maxi-mum yield strength at 600 °C and elevated temperatures is presented in Ni₅₀Ti₄₃Al₆Mo₁ alloy not in alloys with a higher Mo content, which is possibly due to the softness of Mo-Ti-Ni solid solution phase.     

Phase Transformation and Microstructure of Ti50Ni48-xFe2Ndx Shape Memory Alloys

The influences of rare earth element Nd on the phase transformation and the microstructure of Ti₅₀Ni_48−xFe₂Nd_x shape memory alloys are investigated by means of electrical resistivity, optical microscopy, electron probe microanalyzer, and X-ray diffraction. The results show that TiNiFe alloys with different Nd contents exhibit two-step martensitic transformation. The start temperature of martensitic transformation increases sharply from 212 K to 267 K when 0.1 at.% Nd is added in, and then decreases gradually if Nd content further increases. The microstructure of TiNiFeNd quaternary alloys consists of TiNi matrix, Ti₂Ni second phase, and Nd₃Ni intermetallic compound. The spherical Nd₃Ni precipitate-particles evenly disperse in the matrix.     

TiNiFeNb形状记忆合金的组织结构及相变特性

通过向TisoNiso合金中加入Fe和Nb元素,制备出一种四元Ti49Ni50-xFexNb1形状记忆合金.采用X射线衍射和背散射电子衍射的方法,测试和分析了合金的相结构及微观组织形态,采用电阻法系统研究了合金的相变特性.结果表明:Nb元素的加入并没有改变TiNiFe合金的B2结构,仅导致了广极少量的富Nb相在基体中析...     

Effects of Nb Content on Yield Strength of NiTiNb Alloys in Martensite State

Two near single-phase NiTiNb alloys—Ni₅₀Ti₄₈Nb₂ and Ni_49.5Ti_46.5Nb₄—are prepared and studied by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), differential scanning calorimetry (DSC) and tensile tests in order to unearth the effects of Nb-atom solid solution in NiTi phase on the yield strength induced by self-accommodation of martensite variants. The results show that the yield strength of near single-phase NiTiNb alloys varies inversely with the amount of Nb-atoms solid-dissolved in NiTi phase. From the results out of the prior and current studies, it can be surmised that the effects of Nb content on the yield strength of NiTiNb alloys in martensite state depend on the coaction. Nb solid solution weakening mechanism and β-Nb phase composite strengthening mechanism. This inference might be a satisfactory explanation to the fact that the yield strength of (NiTi)_50–0.5xNb_x alloys in martensite state begins with decline and then rises when the Nb content increases.     

Mechanical Properties and Transformation Behavior of NiTiNb Shape Memory Alloys

NiTiNb shape memory alloys have attracted much attention in pipe coupling or sealing system because of their large transformation hysteresis upon a proper pre-deformation. In order to clarify the effects of adding Nb on the mechanical properties as well as the transformation behavior of NiTiNb shape memory alloys, Ni₄₇Ti₄₄Nb₉ and Ni_49.8Ti_45.2Nb₅ alloys with different microstructures but with similar martensitic transformation start temperature, are prepared. Comparative studies on the microstructures, mechanical properties and transformation characteristics are conducted by means of scanning electron microscopy (SEM), phase transformation measurements and mechanical property tests. It is found that Ni₄₇Ti₄₄Nb₉ and Ni_49.8Ti_45.2Nb₅ alloys possess similar transformation hysteresis in the as-annealed state. However, the presence of Nb and its status exerts important effects on the mechanical properties, especially the yield strength and the yield behavior of the alloys. Ni_49.8Ti_45.2Nb₅ alloy exhibits remarkable increase in the yield strength than the Ni₄₇Ti₄₄Nb₉ alloy. The transformation hysteresis of both alloys under pre-deformation is characterized and the relative mechanism is discussed.     

Microstructure and Mechanical Properties of In-situ Synthesized Al2O3/TiAl Composites

Al2O3 particle-reinforced TiAl composites are successfully reaction-synthesized from the powder mixture of Ti, Al, TiO2, and Nb2O5, using the hot pressing reaction synthesis technique. The microstructure and mechanical properties of the as-sintered products are investigated. It is found that in the as-sintered products consisting of γ-TiAl, α2-Ti3Al, Al2O3, and NbAl3 phases, the fine Al2O3 particles tend to disperse on the grain boundaries. With the Nb2O5 content increasing, the grains are remarkably refined and the Al2O3 particles are dispersing more uniformly in the TiAl matrix, forming a partial lamellar structure containing α and lamellar phases. The hardness of the in-situ composites increases gradually, and the bending strength and the fracture toughness of the as-sintered products reach the maximum value of 398.5 MPa and 6.99 MPa·m^1/2, respectively, as the Nb2O5 content increases to 6 wt%.     

新型Co基合金Co-9Al-(9-x) W-xMo-2Ta-0.02B的显微组织与高低温力学性能

以新型Co基合金Co-9Al-9W-2Ta-0.02B成分为基础,分别添加了原子分数为2％、4％、6％、9％的Mo元素替代W（分别称2Mo、4Mo、6Mo、9Mo合金,W+Mo的原子分数为9％,无Mo添加的称为0Mo合金）,研究了Mo元素对合金相组成、显微组织形貌、维氏硬度和高低温压缩强度的影响.结果表明铸态合金由Co...     

Influence of welding parameters on microstructure and mechanical properties of electron beam welded Ti60 to GH3128 joint with a Cu interlayer

Effects of welding parameters on the microstructure and mechanical properties of Ti/Cu/Ni joint welded by electron beam were investigated. High welding heat input increased the melting quantity of Ti60 titanium alloy and promoted the formation of Ti–Cu intermetallic compounds (IMC) such as Ti₂Cu and Ti₃Cu₄, increasing the brittleness of the joints. Low welding heat input was not conducive to the complete melting of the copper interlayer, and the unmelted copper reduced the performance of the joints. Under the optimal welding parameters, Ti–Ni IMCs in the weld would be replaced by (Cu, Ni) solid solutions ((Cu, Ni)_ss). However, Ti–Cu IMC layers cannot be eliminated entirely by changing the welding parameters. The maximum tensile strength of the joints was 201 MPa. The fracture of the joints occurred at the Ti–Cu IMC layer, which was a typical brittle fracture.