铜对高硼铁基合金性能的影响

高硼铁基合金中由于硼的存在,加入的锰、铬等用来增加淬透性的元素大部分形成了硼化物,影响了材料的淬透性。而且由于高硼铁基合金中的硼化物导热性能不好,也会影响到材料的淬透性。本文通过添加铜来研究其提高材料淬透性的效果。铜在钢中的作用与镍类似,可以提高钢的淬透性,含量适当时可以提高钢的冲击韧度。在硼钢中,铜的加入可以提高硼在钢中的溶解度,从而可以改善硼钢晶间硼化物的形态,提高钢的力学性能。在高硼铁基合金中,铜不与硼反应,而且不溶于硼化物中,可以充分发挥其增加淬透性的作用。实验结果表明,铜可以有效的增加高硼铁基合金的淬透性,并且可以提高其冲击韧度。     

ENVIRONMENTAL DAMAGE OF CAST Ni-BASE SUPERALLOY K17

Rupture and tensile properties of K17 before and after thermal exposure in vacuum,air andhot corrosion environments have been investigated.The results show that vacuum exposure es-sentially does not affect the rupture lives but it results in the decrease of high temperature ten-sile strength and increases of rupture and high temperature tensile ductilities;air or hot corro-sion environmental exposure results in the degradation of alloy:severely reduce the ruptureand high temperature tensile properties,hot corrosion environmental exposure being moreharmful.The former causes grain boundary oxidation and depletion of Cr,and the latermakes the sulphurization at grain boundaries.This results in the concentration of S and de-pletion of Cr at grain boundaries and,consequently,weakens the grain boundaries.     

K17镍基铸造高温合金环境损伤的研究

本文研究了镍基铸造高温合金K17在真空、空气和热腐蚀环境中热暴露前后持久性能和高温拉伸性能的变化.结果表明,真空中热暴露对K17合金的持久寿命没有影响,但降低高温瞬时拉伸强度,提高持久塑性和高温瞬时拉伸塑性;空气和热腐蚀环境中热暴露明显降低持久性能和高温瞬时拉伸性能,其中尤以热腐蚀环境最严重,空气环境暴露造成晶界氧化并贫Cr,热腐蚀环境暴露引起晶界严重硫化,晶界两侧贫Cr富S,因而弱化晶界,降低性能.     

Effect of High Configuration Entropy and Rare Earth Addition on Boride Precipitation and Mechanical Properties of Multi-principal-Element Alloys

A series of multi-principal-element (MPE) alloys have been prepared by adding Ni, Mn, Al, Cu and Y into the reference CoCrFe-B alloy. The microstructure and mechanical properties of these MPE alloys have been investigated thoroughly. It is found that the addition of the elements can inhibit boride precipitation in the designed alloys and the solid solution strengthening effect induced by interstitial boron atoms is more significant than that by boride precipitation. The MPE alloys with the fcc phase as the main solid solution phase have a higher boron solubility and hence less boride precipitation, than those with the bcc phase as the main solid solution phase. The addition of yttrium can improve the boron solubility, decrease boride precipitation, control the boride morphology and, importantly, simultaneously improve the compressive strength and ductility of boron-containing MPE alloys.     

细化晶粒对改善MGH956合金板材低温脆性的影响

通过对比粗、细两种晶粒组织状态的MGH956合金板材,在光滑和缺口拉伸条件下的韧脆转变温度(Ductile-BrittleTransition Temperature,DBTT),及高温持久性能,研究了细化晶粒对改善MGH956合金板材低温脆性的作用,及高温持久强度的影响。结果表明:细化晶粒有效地改善了MGH956合金板材的低温脆性,明显降低其DBTT,在应力集中程度极高的缺口拉伸条件下,细晶板材的DBTT仍可保持在-15℃以下,同时具有较高的高温持久强度。     

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF A Ni_3Al-Fe BASED ALLOY

The microstructure,tensile properties at 20—950℃ and creep rupture properties at 700-900℃ in a Ni_3Al-Fe based alloy after high temperature deformation have been studied.Theresults show the microstructure of the alloy is composed of γ′-and β-phases.The grain sizeand yield strength of the alloy is stable when the temperature≤600℃,and it is ductile athigh temperature.The creep of the alloy at 700—900℃ is controlled by the climbing of dislo-cations,and the activation energy for creep is 439 KJ/mol with a stress exponent of 4.     

PSR-1涂层合金组织稳定性探讨

加涂PSR-1(NiCrBSi系)的FNA涂层气阀在生产上使用已超过6000小时,PSR-1合金是一由Ni—Cr固溶体和高硬度的硼,碳化物质点组成的多相结构,具有很好的耐磨耐蚀性。本文着重研究了该涂层合金在内燃机的燃气腐蚀疲劳工作条件下的演变规律,经对使用前后的涂层气阀分析解剖表明:涂层与基体之间的互溶区由富Ni固溶体转变成富Fe固溶体,影响到涂层组织和成分变化。分析指出:Fe在涂层中的扩散是硼化铬转变成含铁硼化铬的诱导因素,Cr的重新分布同样受Fe扩散所控制,硼在钢中扩散未导致气阀机械性能恶化,分析认为:在气阀使用工况下,PSR-1涂层组织稳定性是满意的。     

Microstructures and Mechanical Properties of a Newly Developed Austenitic Heat Resistant Steel

The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.     

Influence of alloy ingredients on mechanical properties of ternary boride hard alloy clad materials

Using Mo, B-Fe alloy and Fe powders as raw materials, and adding C, Cr and Ni ingredients, respectively, or C, Cr and Ni mixed powders, ternary boride hard alloy clad materials was prepared on Q235 steel substrate by means of in-situ reaction and vacuum liquid phase sintering technology. The influence of alloy ingredients on the mechanical properties of ternary boride hard alloy clad materials was investigated. The results indicate that a mixture of 0.8% C, 5% Cr and 2% Ni ingredients gives a ternary boride hard alloy clad material with optimal mechanical properties, such as high transverse rupture strength, high hardness and good wear resistance.     

硼对工业纯Al导电性的影响

研究子硼对工业纯Ａｌ导电性的影响,研究结果表明：使用Ａｌ－３．３５％Ｂ中间合金,处理含过渡元素（Ｔｉ,Ｖ,Ｃｒ,Ｍｎ）为０．０１￣０．０２３％的工业纯Ａｌ电阻率都有一定程度的降低,过渡元素含量愈多,效果明显,加入硼后,反应生成块状Ｔｉ,Ｖ,Ｆｅ的硼化物和团絮状Ｔｉ,Ｖ,Ｆｅ,Ｚｒ的硼化物,加硼后使Ｔｉ,Ｖ,Ｚｒ脱离固溶状态,形成硼化物析出,是增加Ａｌ导电性的主要原因,对生成的硼化物进行分析,未发现     

两种含硼Ni3Al合金的微观组织与力学性能

本文研究了两种不同硼含量Ｎｉ３Ａｌ合金的微观组织、室温拉伸及高周疲劳性能，Ｎｉ３Ａｌ（０．６ａｔ．－％Ｂ）合金为单相组织，Ｎｉ３Ａｌ（１．０ａｔ．－％Ｂ）合金中除γ相外，还有微量共晶体，虽然Ｎｉ３Ａｌ（１．０Ｂ）的拉伸强度较Ｎｉ３Ａｌ（０．６Ｂ）的高，但在相同的循环应力水平下，后者的疲劳寿命显著高于前者的，疲劳断口观察表明两种合金的疲劳裂纹萌生和扩展行为各不相同。     

硼含量对镍基合金GH4049晶界析出相和高温性能的影响

在晶界面上用萃取碳复型技术研究了镍基合金GH4049(Ni-15Co-10Cr-5．5W-5Mo-4．2Al-1．5Ti)中与B和C的晶界偏聚效应密切相关的二次析出相特征．B含量低于0．008％时,因固溶B／C(原子比)很低,晶界析出大尺寸MC薄膜和M6C枝晶片以及薄膜状M23C6,不利于高温塑性和持久寿命．B含量为0．011％和0．018％时,固溶B／C(原子比)虽仅为0．667和0．941,已可减少和全部抑制上述碳化物的析出,代之以弥散M3B2颗粒,高温性能大幅度上升．但B含量过高,M3B2密集析出,高温性能下降．降低固溶冷却速度而使B和C原子向晶界长程偏聚,可促进M3B2析出,改善MC的形貌并抑制M6C和M23C6析出。     

高强韧Mo-0.1Zr合金的制备、性能及组织

采用球磨制备Mo-0.1Zr粉末,经压制成型、预烧、高温烧结和真空热处理后,制备抗拉强度超过650 MPa、伸长率大于30%的高强韧Mo-0.1Zr合金,研究真空热处理对合金性能与显微组织的影响。结果表明:经高温烧结后,Mo-0.1Zr合金与纯Mo相比性能提高不明显,断口形貌呈明显的沿晶脆性断裂特征;但经真空热处理后,Mo-0.1Zr合金的性能显著提高,抗拉强度提高了40%、伸长率从7.3%提高到31.2%,合金断口也由沿晶脆性断裂转变为穿晶韧性断裂,且部分晶粒呈韧性撕裂特征。真空热处理温度对合金性能的影响很大,真空热处理温度过高容易使晶粒长大,导致性能提高程度下降;而真空热处理温度过低难以起到消除晶体缺陷的作用,对合金性能提高有限。     

固溶温度对改型In617合金组织和性能的影响

通过光学显微镜(OM)、扫描电镜(SEM)表征、EDS分析以及力学性能测试等方法研究了固溶温度对改型Inconel617(In617)合金组织和性能的影响。结果表明,改型In617合金在950~1200 ℃固溶2.5 h,平均晶粒尺寸从18 μm增长至183 μm;并建立了改型In617合金在950~1200 ℃固溶处理过程中的晶粒长大动力学模型。当固溶温度为1000 ℃时,晶界处M₂₃C₆碳化物回溶;超过1100 ℃固溶时,M₆C碳化物也基本回溶完毕,合金中仅存大尺寸MC型碳化物。随着固溶温度升高,混晶现象发生,合金高温强度逐渐降低,主要归因于碳化物的逐步回溶。其中在1050 ℃固溶时,由于晶界碳化物没有回溶完毕,所以此时改型In617合金的强度下降幅度不高,而当固溶温度达到1200 ℃时,晶界处碳化物消失,晶粒已经长大,导致合金强度大幅降低。     

微量Zr对铸造TiAl合金高温力学性能的影响

在Ti-47.5Al-2.5V-1.0Cr合金中添加0.2at.％Zr以研究微量Zr对铸造形成的定向层片组织高温力学性能的作用.结果表明,添加0.2at.％Zr显著提高了该合金的持久寿命,但未对其高温拉伸强度产生明显影响.根据两种合金持久试验前后组织对比观察的结果提出,添加微量Zr主要是通过增加定向层片组织的热稳定性而使其持久性能得以改善;另外,微量Zr减少了热等静压过程中等轴晶粒的析出,也有助于延长合金的持久寿命.     

固溶工艺对6061铝合金组织和拉伸性能的影响

采用光学显微镜、扫描电镜和拉伸试验等方法,研究了固溶处理工艺对6061铝合金微观组织和力学性能的影响。结果表明,随固溶时间的延长和固溶温度的升高,合金中可溶第二相粒子逐渐溶解,再结晶增强,晶粒细化,合金拉伸性能升高;进一步延长固溶时间和提高固溶温度,合金晶粒粗化,合金强度下降。热处理后残留粗大第二相粒子的多少和合金晶粒大小是影响合金拉伸性能和断口形貌的主要因素。时效工艺为180 ℃×8 h条件下,6061铝合金的最佳固溶工艺为535 ℃×80 min。     

Incipient Melting Behavior and Its Influences on the Mechanical Properties of a Directionally Solidified Ni-Based Superalloy with High Boron ContentEI北大核心CSCD

A new directionally solidified Ni-based superalloy is developed for industrial gas turbine applications, which has high strength and excellent hot corrosion resistance at high temperatures. The high strength of the alloy is primarily derived from precipitation hardening by ordered L12 gamma' phase. To achieve a uniform distribution of precipitated gamma' particles for optimized mechanical properties, the suitable heat treatments are used. However, the heat treatment temperature in Ni-based superalloys is limited by the problem of incipient melting. Incipient melting microstructrue evolution during heat treatment has been hardly reported. Therefore, the behaviors of incipient melting and its effect on mechanical properties in the new directionally solidified superalloy DZ444 with high boron have been investigated in this work. The results show that some interdendritic regions of the as-cast DZ444 sample exhibit many of gamma'/gamma eutectic, MC carbides and multi-phase eutectic-like constituent which are composed of boride, Ni5Hf and eta phases. During solution treatments, incipient melting does not occur in boride or Ni5Hf phase with low melting point firstly, but appears in gamma matrix around multi-phase eutectic-like constituent which is affected significantly by borides. Compared to DZ444 alloy with the normal boron content, incipient melting occurs at the lower temperature in the range between 1160 degrees C and 1170 degrees C. Incipient melting can occur significantly with the increase of the solid solution temperature or time. Incipient melting consists of typical gamma dentrites and a lot of tiny precipitation particles after the water quenching (WQ) method following solution treatment. However, incipient melting forms multi-phase eutectic-like constituent, gamma matrix and gamma'/gamma eutectic successively during air cooling (AC) following solution treatment, and the morphology of multi-phase eutectic-like constituent is similar to that of as-cast alloy. Firstly, a so-called incipiently melted circle (IMC) forms around multi-phase eutectic-like constituent; with the increase of the solid solution temperature or time, IMC extends inwards which makes gamma matrix and multi-phase eutectic-like constituent in this circle melt successively. Finally, a incipiently melted pool forms gradually. Incipient melting is limited to the IMC below 1200. and the area of incipient melting changes with temperature or time correspondingly. However, incipiently melted region (IMR) expands outwards continuously which makes gamma matrix outside the incipiently melted circle melt when the temperature is higher than 1210 degrees C. Especially, IMR swallows up plenty of gamma matrix, and many matrix islands, regions unmelted, exist in IMR above 1250 degrees C which destroys the continuity of the matrix significantly. The incipient melting has a minor effect on the tensile properties, nevertheless, decreases the creep-rupture properties remarkably. The degradation of mechanical properties mainly results from the increasing of the incipient melting area fraction and size.     

细化剂与冷却方式对K438合金组织和高温性能的影响

采用模壳面层细化与风冷/空冷相结合,研究了熔模精铸K438合金凝固组织及沉淀相形成规律,提出了改善合金高温力学性能的途径。结果表明,模壳面层细化为凝固过程提供了有效形核质点,促进凝固组织从柱状晶向等轴晶发生转变,有效地细化了合金的晶粒组织。风冷方式抑制了枝晶熟化和沉淀相粗化,显著降低二次枝晶间距及γ′析出相尺寸。截面等轴晶比例的增加有利于提高合金980℃/150 MPa高温持久性能。枝晶组织的细化及细小沉淀相的形成可以改善合金650℃高温拉伸强度,其中风冷试棒的高温屈服强度和伸长率分别为734 MPa和11%,相比空冷态分别提高了5%和41%。     

微量硼和应变速率对变形TiAl合金室温力学性能的影响

以形变Ｔｉ４７Ａｌ２Ｍｎ２Ｎｂ合金为对象,研究了微量硼合金化和应变速率对ＴｉＡｌ合金室温力学性能的影响。发现添加微量（１．０％,摩尔分数）硼就能有效地细化形变Ｔｉ４７Ａｌ２Ｍｎ２Ｎｂ合金的近全片层组织,显著提高其室温强度,并在一定程度上改善室温塑性;变形ＴｉＡｌ合金不论添硼与否,其室温强度均随应变速率的升高而升高,而延伸率对应变速率不太敏感;微量硼合金化和应变速率对变形ＴｉＡｌ合金室温断裂方式无明显影响。     

高硼铁基耐磨熔覆层研究进展

高硼铁基合金是一种原位生成硼化物硬质相的铁基耐磨材料,具有高硬度、良好的高温稳定性以及低成本的优势,近年来受到了广泛的研究,国内外大量研究通过对硼化物形态进行调控,以达到抑制裂纹以及提高耐磨性能的目的。从材料体系和熔覆层制备技术2大方面系统地综述了高硼铁基耐磨熔覆层近年来的研究进展。首先重点介绍了Fe–B–C、Fe–B–Cr–C、Fe–B–Cr–Mo–C等3种常见的高硼铁基材料体系,详细阐述了各体系合金成分与原位生成硼化物硬质相类型、形态、分布间的相互作用规律,并给出各体系硼化物随成分含量变化的显微形貌图。归纳总结了成分设计及热处理工艺对合金组织演变及耐磨性能的影响,并分析了其他元素对高硼铁基合金组织性能的影响。其次,介绍了高硼铁基耐磨熔覆层制备技术,包括等离子熔覆、激光熔覆、电子束熔覆与氩弧熔覆,分析了如复合热源和外加磁场等可行的熔覆技术改进方法,并讨论了制备工艺对熔覆层的影响。最后对高硼铁基材料未来的研究及应用方向进行了展望。