Ni－Ti－Nb宽滞后记忆合金的显微组织和力学性能

用金相显微镜、电子探针及低温拉伸试验研究了采用不同熔炼方法获得的Ｎｉ－Ｔｉ－Ｎｂ宽滞后记忆合金的显微组织和力学性能。结果表明，熔炼方法不同会影响合金铸锭中的Ｃ、Ｏ含量；随合金中Ｃ、Ｏ等间隙原子含量的增高，（Ｔｉ，Ｎｂ）＿２Ｎｉ相增多，并趋于呈偏聚态分布，明显降低合金的塑性。（Ｔｉ，Ｎｂ）＿２Ｎｉ相的含量和分布形态是影响合金力学性能的主要因素。     

恒温锻造Ti—Al—Nb—Cr—V系（r＋a2）合金的热处理组织

研究了Ｔｉ－４７Ａｌ合金添加少量Ｎｂ、Ｃｒ、Ｖ元素并经恒温锻造后，在不同热处理制度下的显微组织特征，以及Ｎｂ、Ｃｒ、Ｖ对合金组织的影响。结果表明，Ｔｉ－４７Ａｌ－２ＮＢ－１Ｃｒ－１Ｖ及Ｔｉ－４７Ａｌ－２Ｖ－１Ｃｒ合金的热处理组织形貌主要取决于高温处理的温度。在（ｙ＋ａ）两相区，稍低于Ｔａ温度处理时，ａ相显著粗化，随加热温度的降低，ａ，ｙ两相均明显细化，进一步降低加热温度，发生ｙ相的明显粗化，通过控     

Mn对热作模具钢4Cr3Mo2NiVNb热疲劳性能的影响

采用Ｕｅｄｅｈｏｌｍ法研究热作模具钢４Ｃｒ３Ｍｏ２ＮｉＶＮｂ和添加１．５％Ｍｎ后该钢的热疲劳性能。结果表明，添加１．５％Ｍｎ后，４Ｃｒ３Ｍｏ２ＮｉＶＮｂ钢的热疲劳抗力有所下降。试验结果同时表明，影响热作模具钢低周热疲劳的主要因素是钢的断裂韧性。     

Ti对Ni-Nb玻璃态合金的热稳定性和玻璃形成能力的影响

Ｌｎ基、Ｍｇ基、Ｚｒ基和Ｐｄ Ｃｕ基块体玻璃态合金具有优异的力学性能 ,但其抗压断裂强度并不高 (<2 0 0 0ＭＰａ)。新近开发成功了抗压断裂强度高于 2 0 0 0ＭＰａ的Ｈｆ基、Ｎｉ基和Ｃｕ基块体玻璃态合金 ,Ｎｉ Ｎｂ Ｔｉ三元系大块玻璃态合金的抗压断裂强度超过 30 0 0ＭＰａ。因此 ,研究了Ｎｉ6 0 Ｎｂ40 -ｘＴｉ(ｘ =0～ 40 )玻璃态合金的力学性能、过冷液体的热稳定性和玻璃形成能力。研究用的多元Ｎｉ基合金是由纯镍、铌和钛金属混合配料在氩气氛下电弧熔炼制得的铸锭。合金锭重溶 5次以确保其化学均质性 ,重熔后用铜模铸造法制备…     

Mn对热作模具钢4Cr3Mo2NiVNB热疲劳性能的影响

采用Ｕｏｄｅｈｏｌｍ法研究热作模具４Ｃｒ３Ｍｏ２ＮｉＶＮｂ和添加剂１．５％Ｍｎ后该钢的热疲劳性能。结果表明，添加１．５％Ｍｎ后，４Ｃｒ３Ｍｏ２ＮｉＶＮｂ钢的疲劳抗力有所下降，试验结果同时表明，影响热作模具钢低周热疲劳的主要因素是钢的断裂韧性。     

恒温锻造Ti－Al－Nb－Cr－V系（γ＋α_2）合金的热处理组织

研究了Ｔｉ－４７Ａｌ合金添加少量Ｎｂ、Ｃｒ、Ｖ元素（１ａｔ％－２ａｔ％）并经恒温锻造后，在不同热处理制度下的显微组织特征，以及Ｎｂ、Ｃｒ、Ｖ对合金组织的影响。结果表明，Ｔｉ－４７Ａｌ－２Ｎｂ－１Ｃｒ－１Ｖ及Ｔｉ－４７Ａｌ－２Ｖ－１Ｃｒ合金的热处理组织形貌主要取决于高温处理的温度、在（γ＋α）两相区，稍低于Ｔａ温度处理时，α相显著粗化，随加热温度的降低，α、γ两相均明显细化，进一步降低加热温度，发生γ，相的明显粗化。通过控制高温加热温度及时间，可以有效地控制合金的组织，使其获得全片层、近片层、双态、近双态、近γ以及细化的近γ组织。     

Ti—48Al—2Cr—2Nb金属间的激光表面合金化组织与耐磨性

分别采用氮气及预涂ＴｉＮ粉、碳粉、ＴｉＣ粉等方法对Ｔｉ－４８Ａｌ－２Ｃｒ－２Ｎｂ金属间化合物进行激光表面合金化,制得了分别以ＴｉＮ,ＴｉＣ等硬质耐磨相为增强相的快速凝固“原位”金属基耐磨复合材料表面改性层,并分别在干滑动及磨料磨损条件下测试了所获激光表面合金化改性层的耐磨性。结果表明,对Ｔｉ－４８Ａｌ－２Ｃｒ－２Ｎｂ合金进行激光表面合金化改性处理后显微硬度和耐磨性大幅度提高。     

牙科用钛合金材料

牙用合金材料是生体材料中的一大类。钛合金因为有优异的生物相容性所以特别适于牙用 ,其目前主要使用的合金及性能如下表合金制备方法拉伸强度 /ＭＰａ屈服强度 /ＭＰａ延伸率 /%维氏硬度Ｔｉ 2 0Ｃｒ 0 2Ｓｉ铸造 87466963 18Ｔｉ 2 0Ｐｄ 5Ｃｒ铸造 880 65 95 2 61Ｔｉ 13Ｃｕ 4 5Ｎｉ铸造 70 3 2 1 Ｔｉ 6Ａｌ 4Ｖ铸造 976847 5 1 Ｔｉ 6Ａｌ 4Ｖ超塑成型 95 472 910 3 46Ｔｉ 6Ａｌ 7Ｎｂ铸造 93 3 817 711 Ｔｉ Ｎｉ铸造 470 8190　　纯Ｔｉ和Ｔｉ 6Ａｌ 4Ｖ是牙科及外科主要使用的植入材料。最近又开发出了Ｔｉ 4Ｚｒ、Ｔｉ 5…     

铌钒球铁轧辊材质的试验

采用正交试验寻求Ｎｂ、Ｖ合金元素与变质剂最佳组合以获得性能良好的球铁轧辊材料;对比ＮｂＶ球铁与ＮｉＭｏ球铁的组织、铸造性能、力学性能及断裂韧性,结果表明,ＮｂＶ球铁不亚于ＮｉＭｏ球铁。     

Ti－Al－Ga系及Ti－Al－Nb－Cr系α（α_2）／γ相平衡的研究

利用电子探针微区成分分析测定了Ｔｉ—Ａｌ—Ｇａ系，Ｔｉ—Ａｌ—Ｎｂ—Ｃｒ系低Ｇａ，低Ｎｂ和低Ｃｒ部分的α（α_２）／γ相平衡成分，推得了合金元素Ｇａ，Ｎｂ和Ｃｒ在α（α_２）／γ平衡相中的成分分配比Ｋ并利用分配比方程计算出了Ｇａ，Ｎｂ和Ｃｒ在不同温度下的γ相的稳定化参数结果表明，Ｇａ，Ｎｂ为γ相稳定化元素，Ｃｒ为α相稳定化元素．     

合金元素在ZrCr2 Laves相中的晶格占位及其对力学性能的影响

应用Rietveld模拟计算和实验X射线衍射分析合金元素V、Nb和Mo在ZrCr2 Laves相金属间化合物中的晶格占位，研究合金化对ZrCr2 Laves相力学性能的影响。研究结果表明：合金元素V和Mo占据ZrCr2 Laves相金属间化合物中Cr原子的晶格位置，而Nb则占据Zr原子的晶格；添加合金元素V、Nb和Mo使ZrCr2 Laves相化合物硬度及脆性度降低，断裂韧度显著提高，即合金化对ZrCr2 Laves相起软化作用。初步探讨合金元素对ZrCr2 Laves相力学性能的影响机制。     

一种核电用镍基合金焊丝熔敷金属的组织与性能

通过采用JMatPro软件,OM,SEM,TEM等手段分析了试制镍基合金焊丝GTAW熔敷金属的组织与力学性能. 结果表明:试验焊丝熔敷金属金相组织主要由柱状树枝晶γ相(NiCrFe固溶体)、枝晶间富Mo和Nb的偏析γ相以及枝晶间分布的(Nb,Ti)C碳化物、(Ni,Cr,Fe)₂(Nb,Mo)型Laves相、MoCrFe型σ相等组成. Mo,Nb等元素在组织中存在偏析现象,相比于焊丝化学成分,熔敷金属中枝晶干γ相Fe含量较高,Mo,Nb含量较低,而枝晶间Mo,Nb含量较高、Fe含量较低. 熔敷金属室温、350 ℃高温抗拉及屈服强度较高、塑性较好,室温拉伸断口形貌以沿晶分布的韧窝为主,在韧窝底部存在密集的析出相.     

Mo effect on the phase stability and room-temperature fracture toughness of Nb/Nb_5Si_3 in-situ composites

Nb/Nb5Si3 in-situ composites are very attractive structural materials because these materials perform a good balance in mechanical properties, including high strength at high temperature (>1000℃) and reasonably high fracture toughness at room temperature. Metastable phase Nb3Si plays an important role in the properties of     

合金元素对Laves相增强Nb基合金的相组成

采用机械合金化与热压烧结工艺制备了添加合金元素V和Fe的Laves相增强的Nb基复合材料。研究了添加质量分数4%V和Fe的Nb/NbCr2-4.0V和Nb/NbCr2-4.0Fe配比成分的元素粉,经MA20h后在1250℃热压30min所获得的Nb/NbCr2合金的组织和性能。结果表明:在热压过程中原位合成出细小弥散分布的三元Laves相Nb(Cr,V)2和Nb(Cr,Fe)2,并且V和Fe原子只占据Laves相中的Cr原子位置。制备出的Laves相增强Nb基合金接近全致密,组织细小均匀,晶粒尺寸小于500nm。Nb/NbCr2-4.0V和Nb/NbCr2-4.0Fe合金的断裂韧性分别达到5.3和6.3MPa·m1/2,其中Nb/NbCr2-4.0Fe合金不仅抗压强度达到2256MPa,其屈服强度和塑性应变也分别达到2094MPa和6.03%。     

Mechanical properties of spark plasma sintered Nb–Al compacts strengthened by dispersion of Nb2N phase and additions of Mo and W

Mechanically alloyed and blended Nb–Al–N powders were sintered by the spark plasma sintering process, and their microstructure and mechanical properties were investigated. All of the Nb–Al–N compacts consisted of phases in the Nb–Al system in which the Nb₂N phase was dispersed. The microstructure of blended powder compacts was much coarser than that of mechanically alloyed powder compacts. The compacts obtained by sintering powder produced by crushing blended powder compacts have finer microstructure, higher hardness, and higher fracture toughness than blended powder compacts. The strength of Nb–Al–N compacts increases with increasing the fraction of AlN added to the Nb powder, while their fracture toughness at room temperature decreases. As for the Nb–Al–Mo and Nb–Al–W system, the effect of solid-solution hardening of W was larger than that of Mo, and Nb–15Al–40Mo compact has the highest strength at room temperature and 1273 K among Nb–15Al–xMo compacts.     

Microstructure and properties of novel quinary multi-principal element alloys with refractory elements

Five equiatomic alloys(Ti Zr Hf VNb, Ti Zr Hf VTa, Ti Zr Nb Mo V, Ti Zr Hf Mo V and Zr Nb Mo Hf V) composed of five elements with high melting temperature, respectively were prepared by arc-melting to develop a novel high temperature alloy. The five alloys exhibit different dendritic and interdendritic morphologies. The Ti Zr Hf VNb, Ti Zr Hf VTa and Ti Zr Nb Mo V alloys formed disordered solid solution phases with body-centered cubic structure, and exhibited high compressive strength and good plasticity. The Ti Zr Hf Mo V and Zr Nb Mo Hf V alloys are composed with Laves phase(Hf Mo2) and disordered solid solution phases with body-centered cubic structure. The Ti Zr Hf Mo V and Zr Nb Mo Hf V alloys are harder and more brittle than the other three alloys due to the existence of hard and brittle Laves phases. At high temperatures, the strength decreases to below 300 MPa for the Ti Zr Hf VNb and Ti Zr Hf Mo V alloys. Solution strengthening is the primary strengthening mechanism of the Ti Zr Hf VNb, Ti Zr Hf VTa and Ti Zr Nb Mo V alloys, and brittle Laves phase is the main cause for the low ductility of the Ti Zr Hf Mo V and Zr Nb Mo Hf V alloys.     

Laves相TiCr2基金属间化合物的研究进展

Laves相铬化物以其熔点高、适当的密度和良好的高温强度成为重要的潜在高温结构材料。对Laves相TiCr2金属间化合物的研究进展进行了综述,重点对TiCr2的性质及其基础研究、热力学性能以及TiCr2的合金化研究现状进行了论述。     

热等静压和热处理对快凝NiAl-Cr(Mo)-Hf共晶合金显微组织和压缩性能的影响

快速凝固可明显细化NiAl-Cr(Mo)-0.5Hf共晶合金的组织,使合金中的富Hf相部分以Hf固溶体的形式存在,改善了Heusler相(Ni_2AlHf)和Hf固溶体的形态和分市,明显提高了合金的室温压缩性能.快凝合金热等静压或高温热处理后,合金中的Heusler相进一步向Hf固溶体转变,而且Heusler相和Hf固溶体均由原来的近连续分布转变为不连续分布;热等静压处理快凝合金中的初生NiAl相呈现粗化的趋势,而高温热处理快凝合金中的初生NiAl相有所减少.热等静压和高温热处理工艺进一步改善了快凝合金的高温压缩性能.     

2％C／MoSi2复合材料的组织结构与性能

采用热压烧结工艺制得了2％C／MoSi2（质量分数）复合材料,并测定了材料的显微组织和结构、室温和高温力学性能、耐磨性能以及电阻率。结果:C／MoSi2复合材料由大量的MoSi2、多量的Mo5Si3和少量的β－SiC组成,其硬度Hv为1060,抗弯强度为470MPa,断裂韧性为5．12MPa.m^1/2,800℃的硬度Hv为750,1200℃的抗压强度为450MPa,1400℃的抗压强度为142MPa;在Al2O3和SiC磨盘上表现出优异的耐磨性能,材料的电阻率为349n.m。与纯MoSi2相比,2％C／MoSi2复合材料在硬度、抗弯强度、断裂性、高温抗压强度、弹性模量和耐磨性能等方面都有较大的提高。     

Effect of Nb and Mo on the Microstructure,Mechanical Properties and Ductility-Dip Cracking of Ni–Cr–Fe Weld Metals

A series of Ni–Cr–Fe welding wires with different Nb and Mo contents were designed to investigate the effect of Nb and Mo on the microstructure, mechanical properties and the ductility-dip cracking susceptibility of the weld metals by optical microscopy(OM), scanning electron microscopy, X-ray diffraction as well as the tensile and impact tests. Results showed that large Laves phases formed and distributed along the interdendritic regions with high Nb or Mo addition. The Cr-carbide(M_(23)C_6) was suppressed to precipitate at the grain boundaries with high Nb addition. Tensile testing indicates that the ultimate strength of weld metals increases with Nb or Mo addition. However, the voids formed easily around the large Laves phases in the interdendritic area during tensile testing for the weld metal with high Mo content. It is found that the tensile fractographs of high Mo weld metals show a typical feature of interdendritic fracture. The high Nb or Mo addition, which leads to the formation of large Laves phases, exposes a great weakening effect on the impact toughness of weld metals. In addition, the ductility-dip cracking was not found by OM in the selected cross sections of weld metals with different Nb additions. High Nb addition can eliminate the ductility-dip cracking from the Ni–Cr–Fe weld metals effectively.