内生TiC颗粒增强NiAl基复合材料的初步研究

用ＨＰＥＳ工艺合成了２０ｖ．％ＴｉＣ颗粒增强的ＮｉＡｌ基复合材料，其维氏硬度、压缩屈服强度都比单相ＮｉＡｌ有大幅度提高。特别是室温和１０００℃以上，屈服强度比基体提高近二倍，室温塑性也优于单相ＮｉＡｌ。     

La对富Ni的NiAl系合金组织与性能的影响

通过压缩和三点弯曲试验对加Ｌａ后富Ｎｉ的ＮｉＡｌ合金力学性能进行了考察。结果发现,Ｌａ的加入可以明显地细化合金的晶粒及改善ＮｉＡｌ和Ｎｉ３Ａｌ的两相分布。适量Ｌａ可提高合金的室温屈服强度和塑性,但超过一定的含量,合金的塑性反而有所下降。在合金中,引入Ｂ韧化的Ｎｉ３Ａｌ对合金的塑性有利。     

Fe_3Al金属间化合物强韧化研究进展

Ｆｅ３Ａｌ基合金作为一种金属间化合物新型结构材料越来越引起人们的重视，极有可能在许多场合得到应用。但是Ｆｅ３Ａｌ合金室温时的低塑性和低的断裂抗力以及高于６００℃时强度的急剧下降妨碍了它的工程应用，本文主要综述近几年来Ｆｅ３Ａｌ金属间化合物机械性能方面的研究情况。     

Fe3Al金属间化合物强韧化研究进展

Ｆｅ３Ａｌ基合金作为一种金属间化合物新型结构材料越来越引起人们的重视，极有可能在施工场合得到应用。但是Ｆｅ３Ａｌ合金室温时的低塑性和低的断裂抗力以及高于６００℃时强度的急下降妨碍了它的工程应用，本文主要综述近几年来Ｆｅ３Ａｌ金属间化合物机械性能方面的研究情况。     

V对Fe3Al基有序合金力学性能的影响

研究了微量Ｖ对ＤＯ３型Ｆｅ３Ａｌ基合金伸性能和组织结构的影响。结果表明，Ｖ可细化晶粒，改善Ｆｅ３Ａｌ合金室温强度和塑性，室温伸断口也由穿晶解理型转变为加沿晶混合型，Ｖ还使Ｆｅ３Ａｌ合金高温强度峰值对应的温度提高约２００℃，从而提高Ｆｅ３Ａｌ合金高温强度峰值对应用温度提高约２００℃，从而提高Ｆｅ３Ａｌ合金使用温度。     

（Ni,Fe）Al金属间化合物的快速凝固组织与室温塑性

用单辊快速凝固法制备（ＮｉＦｅ）Ａｌ金属间化合物并研究其组织与室温塑性。结果表明，Ａｌ－４５Ｎｉ－５Ｆｅ（原子分散）在快速凝固条件下可形成内部为亚微米级针状亚晶的等轴晶粒，具有高达３．１％的弯曲塑性，Ａｌ－３５Ｎｉ－１５Ｆｅ和Ａｌ－２５Ｎｉ－２５Ｆｅ的快凝组织则为柱状晶，弯曲塑性仅有１．１％１．０％，针状亚晶是一定成分的（Ｎｉ，Ｆｅ）Ａｌ在快速凝固条件下形成的亚稳相，其形成机制和快速凝固过程中原子     

钛对金属间化合物Fe－36．5at％Al力学性能的影响

研究了２ａｔ％Ｔｉ元素对Ｂ２结构Ｆｅ－３６．５ａｔ％Ａｌ金属间化合物组织和从室温至高温拉伸性能的影响。结果表明，Ｔｉ元素完全面溶于ＦｅＡｌ合金，使ＦｅＡｌ合金高温性能有所提高，同时亦提高低温强度和中温塑性，对低温塑性没有改善。Ｔｉ不改变ＦｅＡｌ合金的变形机理，亦不改变合金断裂模式，仅使７００℃以下温度时混合断口形貌中沿晶断裂部分所占比例增加。     

NiAl（Fe）合金组织和拉伸性能的研究

采用光学显微镜、扫描电镜（ＳＥＭ）、透射电镜（ＴＥＭ）、电子探针（ＥＰＭＡ）、Ｘ射线（ＸＲＤ）和选区电子衍射分析（ＳＡＥＤ）研究了ＮｉＡｌ（Ｆｅ）合金的显微组织及拉伸性能。结果表明，铸态ＮｉＡｌ（Ｆｅ）合金经均匀化退火后的组织由β及β＋γ＇相组成。韧性相γ＇相能阻止裂纹扩展，有利于改善合金的室温塑性。比较发现，Ｎｉ５０Ａｌ２０Ｆｅ３０合金具有最佳的室温塑性，其拉伸断口由β相的解理断口和β＋γ＇相的     

NiAl基金属间化合物的研究进展

介绍和评述了NiAl基金属间化合物的研究进辰。由于NiAl基金属闻化合物的一些优异性能，长期以来作为高温结构的候选材料而得到了广泛的关注，但是NiAl在室温下塑性差和高温时强度低限制了它的使用。着重介绍了对NiAl的晶体结构和缺陷、力学性能、化学性能等方面的研究，利用控制显微结构、合金化和改进加工技术等方法改善了NiAl的室温塑性和高温强度。     

添加Al_2O_3对SiC板粒／Y－TZP复合材料力学性能的影响

本文以ＳｉＣ板粒、ＺｒＯＣｌ２－８Ｈ２Ｏ、ＡｌＣｌ３和Ｙ（ＭＯ）３为原料，利用共沉淀和热压烧结工艺，制备ＳｉＣ板粒／Ｙ－ＴＺＰ和（含Ａｌ２Ｏ３）ＳｉＣ板粒／Ｙ－ＴＺＰ复合材料．测试了材料的室温和高温力学性能．研究了添加Ａｌ２Ｏ３对ＳｉＣ板粒／Ｙ－ＴＺＯ复合材料的影响．结果表明，ＳｉＣ板粒／Ｙ－ＴＺＰ复合材料与Ｙ－ＴＺＰ陶瓷相比，其室温强度和韧性出现明显下降，高温强度也没有改善；而在ＳｉＣ板粒与Ｙ－ＴＺＰ复合的基础上，添加Ａｌ２Ｏ３可明显提高材料的强度和断裂韧性，同时，材料的高温强度也获得显著改善．     

Carbon fibre reinforced carbon produced by polymer impregnation and pyrolysis

Carbon fibre reinforced carbon (C/C) is an attractive material for intermediate and high temperature applications due to its specific properties like low density, high strength and chemical stability. Unfortunately the material oxidizes, so that in an oxidative environment a protective coating has to be applied. Polymer impregnation and pyrolysis is a cost effective production technique to produce C/C materials. In the present work, an abstract of a research program funded by the German Science Foundation (DFG), the mechanical properties of C/C as a function of processing temperature and test temperature have been described. In the program the behaviour of two-dimensionally reinforced (2D) material and unidirectional reinforced (1D) materials has been investigated. All materials experience a strength reduction as a result of carbonization of the polymer matrix at temperatures up to 1000°C. An additional heat treatment above 1000°C causes a partial recovery of the strength. The 1D C/C material shows up to testing temperatures of 1800°C a 10 % loss of strength, whereas for the 2D C/C the strength increases by 10 % at 1500°C in comparison with the room temperature results.     

Electron-beam irradiation effects on mechanical properties of PEEK/CF composite

Carbon fibre-reinforced composite (PEEK/CF) using polyarylether-ether-ketone (PEEK) as a matrix material was prepared and electron-beam irradiation effects on the mechanical properties at low and high temperatures were studied. The flexural strength and modulus of the unirradiated PEEK/CF were almost the same as those of carbon fibre-reinforced composites with epoxide resin. The mechanical properties at room temperature were little affected by irradiation up to 180 MGy, but in the test at 77 K the strength of the specimens irradiated over 100 MGy were slightly decreased. The mechanical properties of the unirradiated specimen decreased with increasing testing temperature, but the high-temperature properties were improved by irradiation, i.e. the strength measured at 413 K for the specimen irradiated with 120 MGy almost reached the value for the unirradiated specimen measured at room temperature. It was apparent from the viscoelastic measurement that the improvement of mechanical properties at high temperature resulted from the high-temperature shift of the glass transition of the matrix PEEK caused by radiation-induced cross-linking.     

Mechanical and Electrical Properties of Cryo-worked Cu

For manufacturing the magnets of fusion machines pure copper of both high mechanical resistance and electrical conductivity is required. Though high purity copper guarantees high electrical conductivity, its mechanical properties may be not suitable for the applications in tokamaks. In this view, a new procedure developed for obtaining high purity copper with excellent mechanical strength is described in this work. Samples of oxygen free copper (OFC) have been worked by pressing in liquid nitrogen (77 K). It has been verified that the mechanical properties of the worked metal are strongly dependent on the strain rate. Very low strain rates permitted to attain values of tensile yield strength (550 MPa) significantly higher than those obtained by traditional cold-working at room temperature (450 MPa). The electrical conductivity of the cryo-worked Cu decreases with the tensile yield strength even though the hardest samples of tensile yield strength of 550 MPa exhibit still acceptable values of conductivity (about 94 % IACS at room temperature).     

Room‐Temperature Mechanical Properties of V20Nb20Mo20Ta20W20 High‐Entropy Alloy

Refractory high‐entropy alloys (HEAs) have shown promising high temperature strengths, while their mechanical behaviors at room temperature are rarely reported. In this work, the room‐temperature mechanical properties of V₂₀Nb₂₀Mo₂₀Ta₂₀W₂₀ refractory HEA under various different loading modes including tension, compression, bending, shear loading, and microhardness are investigated. The results show that this alloy exhibits very high compressive strength but quite low strengths under tension, bending, and shear loading, similar to the conventional brittle materials. However, pronounced plasticity and slip bands are observed in compression samples, and no indentation cracking is observed in low‐load microhardness tests, which indicate the potential ability of plastic deformation in this refractory HEA. The present work suggests that the microstructure or composition of this HEA should be carefully tailored before its practical usage to suppress its large tendency for cracking and eventually improve its ductility and strength under tension.

     

Structural Applications of NiAl

Alloys based on NiAl offer significant payoffs as structural materials in gas turbine applications due to a unique range of physical and mechanical properties These properties include high melting temperature. low density. high thermal conductivity. and excellent environmental resistance Very significant improvements in the strength and ductility of NiAl single crystals have been achieved through alloying. Tensile strength and stress rupture properties which compete with current Ni-base Superalloys have been achieved through precipitation of an ordered L21 Heusler phase in NiAl single crystals Room temperature tensile ductility as high as 6% has been produced in NiAl single crystals containing less than 0.5% (atomic) of Fe. Ga or Mo. However. a single alloy with both room temperature ductility and sufficient high temperature strength has not yet been developed. While activity to develop on alloy with both high temperature strength and room temperature ductility continues. the Current approach also emphasizes design and test methodologies which can accept a material with limited ductility and damage tolerance More work is required on measuring and understanding strain rate sensitivity and impact behaviour While several significant challenges still remain. excellent progress has been made in many areas, and the prognosis for using NiAl alloys as high temperature structural materials is promising     

High-temperature mechanical properties of aluminium alloys reinforced with boron carbide particles

The mechanical properties of particulate-reinforced metal-matrix composites based on aluminium alloys (6061 and 7015) at high temperatures were studied. Boron carbide particles were used as reinforcement. All composites were produced by hot extrusion. The tensile properties and fracture analysis of these materials were investigated at room temperature and at high temperature to determine their ultimate strength and strain to failure. The fracture surface was analysed by scanning electron microscopy.     

石英纤维布/含乙烯基聚硅氮烷耐高温透波复合材料的制备与性能

在对含乙烯基聚硅氮烷（PSN1）树脂基本性能研究的基础上,以石英纤维布为增强材料,利用层压法制备了石英纤维布/含乙烯基聚硅氮烷耐高温透波复合材料（QF/PSN1）,并对其在室温和高温下的力学性能及介电性能进行了测试与表征。研究结果表明:PSN1树脂工艺性能良好,黏度低于1 Pas（60~151℃）,固化温度小于200℃;耐热性能优异,在N₂和空气氛围下,其固化物失重5%时的温度均高于480℃、800℃时的残重均高于76%。QF/PSN1复合材料力学性能优异,弯曲强度和层间剪切强度随温度升高出现先下降后上升的趋势;450℃烘烤10 min后,其弯曲强度仍在120 MPa以上。QF/PSN1复合材料介电性能优异:在1~12 GHz范围内,QF/PSN1复合材料在室温~450℃范围内介电常数（ε）均低于3.2,介电损耗（tanδ）均小于0.01。上述研究结果表明:含乙烯基聚硅氮烷作为耐高温透波材料的新型树脂基体具有重要的应用价值。      

Technologische Eigenschaften warmgewalzter Bleche großer Formate aus Titan für den Anlagenbau

Mechanical Properties of Hot Rolled Plates of Large Size for Plant Engineering Large size plates of commercially pure titanium grade 1, 2 and 3 according to DIN 3.7025, 3.7035 and 3.7055 up to 3500 mm width and a maximum length of 10000 mm with a thickness of 7 and 30 mm have been tested. They fullfill the acceptance specifications for hot rolled plates of conventional size regarding flatness, thickness tolerances and mechanical properties at room temperature. The availability of plates with a very high flatness creates the basis for large sizes explosion cladding with commercially pure titanium as surface layer material. Additional investigations between ? 196°C and + 400°C for the mechanical properties and notched impact strength of plates and weldments as well as fatigue strength at room temperature show, independent of the rolling direction, the possible influence of grain size and interstitials like oxygen and hydrogen as well as of the iron content on the properties. The notched impact strength has a maximum at 100°C without a steep drope at lower temperatures. The decrease of tensile strength and proof stress with increasing temperature show a retarding effect at 150°C. The elongation reaches a maximum at 200°C, combined with a low ratio of yield strength to tensile strength.     

泵头体高强钢材料的力学性能

为了进一步研究泵头体高强钢25Cr2Ni4MoV和30CrNi2MoV的力学性能,采用拉伸、冲击和裂纹尖端张开位移(CTOD)试验对其进行测试。结果表明:材料在常温下具有较好的综合力学性能;在静载荷条件下,具有优良的断裂韧度。