合金化对铌基固溶体合金和铌硅化物基合金室温断裂韧性影响的研究进展

Ti、Cr和Al的添加改变了铌基固溶体合金的弹性常数,从而改变了其点阵位移势(UP-N).采用表面能(γs)与点阵位移势(UP-N)之比可预测合金的室温断裂韧性.Ti的添加降低了点阵位移势、提高了位错的移动能力,从而提高了铌基固溶体合金的室温断裂韧性;而Cr和Al的作用与Ti相反.简要介绍了K.S.Chan等建立的室温断裂韧性计算模型,同时介绍了合金化元素Ti、Mo、Hf和B等对铌硅化物基合金室温断裂韧性的影响.其中Ti、Hf和B的添加能提高铌硅化物基合金的室温断裂韧性.     

二元固溶体型合金凝固过程中固相分数的变化规律

本文首先总结了前人在固相分数计算方面的研究工作。通过对几个主要影响因素的分析,指出了以前所用计算式的适用范围。进而通过对作者最近提出的局部溶质再分配方程修正式的求解,得出了板状技晶和柱状枝晶两种生长形态下适用范围更广的计算式。最后以Al—4.5％Cu合金枝晶生长过程为例,对各式的计算结果进行了对比讨论。并估算了非平衡共晶和θ相的析出量。     

高熵合金固溶强化问题的研究进展

区别于传统的合金材料,高熵合金没有溶质溶剂概念的划分.多主元成分配比造成的晶格畸变、尺寸错配等使高熵合金表现出显著的固溶强化效应,因而可获得优异的力学强度.然而,经典合金固溶强化理论中关于稀释溶质的假设并不适用于高熵合金,相关强化模型无法有效预测其力学强度,这阻碍了高熵合金成分的理性设计及相关应用.近年来,基于高熵合金的成分特点,人们不断探究其固溶强化的起源,尝试建立有效的预测模型,实现合金强度的准确预测,进而指导面向性能需求的高熵合金快速设计,最终推动高熵合金的科学研究和工程应用.本文总结了高熵合金固溶强化问题的研究进展,介绍了三种典型的固溶强化模型,对比分析了各模型的建模思路、预测效果、存在问题及在高熵合金设计中的具体应用,最后对高熵合金固溶强化机制的探索、强化模型的发展及应用进行了展望.     

Behaviour of Rare Earths in Solid Solution in Steel

The contents of rare earth metals(REM) insolid solution in 16 Mn steel were determined bymeans of inductive coupling plasma (ICP)spectroscopy.The amount of REM in solid solutionis only a few ppm in the steel with MnS inclusions,which rises slightly with the increasing of REMcontent in steel.At RE/S>1.9,the MnS inclu-sions in steel disappear completely,the REM con-tent in solid solution increases rapidly with the in-creasing of REM content.The solubility of ceriumin 16 Mn steel(st 52)is less than 0.011 wt—％ atroom temperature.The results obtained indicate that REM in sol-id solution reduce the amount of pearlite and in-crease that of ferrite and its microhardness.Dis-solved REM oculd increase temperature of criticalpoints,alleviate band structnre and suppressgrowth of austenite grains.     

材料阻尼及阻尼合金的研究现状

介绍了材料的阻尼特性及其表征参数,综述了近年来在阻尼性能测试方法,阻尼合金及其阻尼机制等方面的研究现状,并指出了传统阻尼合金应用方面的存在的问题。     

Mg-Li-Al合金阻尼性能的研究

研究了MgLi4Al和MgLi8Al合金的阻尼性能,结果表明,Mg-Li-Al合金的阻尼性能随锂含量的增多和温度的提高而明显增高,其中MgAl8Al合金的室温阻尼性能达到Q1＝0．01的高阻尼值,MgLi8Al合金的阻尼明显大于MgLi4Al合金的阻尼是由于MgLi8Al合金相界阻尼的贡献。     

无基元高混合熵合金形成固溶体结构三原则

无基元高混合熵合金是由五种以上主元素构成，具有很高的混合熵。通过对已发表无基元高混合熵合金数据的分析，初步得出无基元高混合熵合金形成固溶体的一般规律：1五种以上主元素；2最大原子半径差小于12％；3舍金混合焓介于-40到10KJ／mol。     

Densification of Mo Alloys at 1473 K by Adding Ni-Cu Solid Solution

Mo is difficult to sinter densely at a relatively low temperature due to its high melting point. In the present paper,by adding different weight contents of Ni and Cu additives, Mo alloys have been densified at 1473 K for an hour byhot-pressing method, and the optimum contents of Cu and Ni additives have been acquired: when the contents of Niand Cu are 3 and 2 wt pct respectively, the relative density of the sample reaches the maximum value. It was foundthat when the Ni-Cu solid solution was added into Mo alloys. the achieved density is higher than the case of Ni andCu additives. The experimental results indicate that, Ni and Cu play different roles in the process of sintering, theNi-Cu solid solution has the same function as Ni and Cu additives in the course of sintering Mo alloys, It shows moreactivating sintering feature for Mo than the Ni and Cu additives.     

不同热处理工艺对Mg–Y–Zn–V合金组织力学性能的影响

目的 探索合适的热处理工艺,以调控合金的晶粒尺寸和LPSO相特征（形貌、类型、体积分数和分布）,从而优化其力学性能。方法 通过改变热处理时间及冷却方式得到一系列Mg–Y–Zn–V合金,利用X射线衍射、光学显微镜、扫描电镜和拉伸测试等手段分析热处理后合金的微观组织及力学性能。结果 在500℃、24 h固溶处理后,通过水冷得到的合金性能最佳,极限抗拉强度为190 MPa,屈服强度为129 MPa,伸长率为18.4%。随着热处理时间的延长,18R相逐渐固溶到基体中,而W相在发生球化后很难进一步固溶到基体,且在不同的冷却方式下LPSO相呈现块状、杆状和针状3种形态。结论 固溶处理后球化的W相和块状18R相可以提高合金性能,而层片状LPSO则会降低合金的力学性能。     

高温退火Fe-Cr基减振合金的阻尼性能与晶界析出相

对1473K退火的Fe-Cr-2Al-Si，Fe-Cr-Al,Fe-Cr-Si以及Fe-Cr-Al-Si(L)等Fe-Cr基减振合金的阻尼性能和晶界析出相进行了研究。结果表明，这些合金中所析出的晶界相均由Cr和Fe两种元素构成，并且合金的阻尼性能与这种晶界相析出量的多少以及晶界相中Cr含量的高低存在对应关系。Fe-Cr-2Al-Si合金中晶界相的析出量最少且Cr含量最低，这种合金的阻尼性能最好；Fe-Cr-Al-Si(L)合口中晶界相的析出量最多且Cr含量最高，该合金的阻尼性能最差；Fe-Cr-Al和Fe-Cr-Si两种合金的晶界析出相中的Cr含量十分接近，但前者晶界相的析出量明显低于后者，前者的阻尼性能亦明显好于后者。     

Effect of Solid Solution Supersaturation on Precipitation of γ'''' in Rapidly Quenched Ni-Al Binary Alloys

The effect of solid solution supersaturation on the precipitation of γ' in rapidly quenched Ni-Al binary alloys containing 11.6, 14.2 and 16.5 at. Pct Al was investigated. The samples were solutioned at 1250℃, quenched in iced brine, and then analyzed by electron microscopy and XRD (X-ray diffraction) techniques. In Ni-11.6 at. Pct Al alloy, ordering and phase separation took place simultaneously, resulting in a uniform distribution of γ'. A transition from uniform to bimodal γ' phase distribution occurred in the composition range between 14.2 and 16.5 at. Pct Al. This transition was accompanied by changes in the morphology of γ' precipitates. The microstructural observations were discussed in view of both kinetics and crystallographic considerations.     

Effect of Molybdate Ions on the Corrosion Behaviour of Ti Alloys

1. IntroductionTitanium alloys are most often specified for industrial and chemical process service due to theirrelatively superior corrosion performance in chlorideand other -halide--containing' environments[1]. Moreoverl Ti-alloys are candidate materials for containersof high-level nuclear waste suitable for deep underground burial for geological formations for extremelylong periods of timelZ]. This is because Ti-alloys canmailltain passivation in the ranges of temperatures,PH and chloride…     

Effects of Additional Elements on Microstructure and Precipitation Behaviour in Rapidly Solidified Al-Ti Base Alloys

Rapidly solidified Al-Ti base alloys were prepared by melt spinning at the cooling rate about 107 K/s. The melt-spun ribbons were used to observe the dricrostructures after heat treatment.In the supersaturated Al-Tl-Si alloy, age hardening occurred after 1 h anneal in the temperature range of 4000~500℃, which seems to be attributed to the precipitation of metastable Ll2- (Al,Si)3Ti phase. However. the microhardness was relatively low because of the low v/o and the insufflcient stability of precipitates. Thus. Cr was added to Al-Ti-Si alloys in order to stabilize the microstructures and to increase the v/o of precipitate5. As a result. the alIoys containing Cr were evaluated to possess the improved properties at the service temperature.     

阻尼合金的种类和特点

阻尼合金是一类新型的金属功能材料,利用其制造相关振动源构件,可以有效地解决机械制造及相关工程领域中的振动和噪声问题。介绍了目前国内外主要研究的阻尼合金的种类、特点和应用范围,并综合对比了各自的阻尼和力学性能,为需要减振降噪场合的选材提供参考。     

阻尼镁合金的研究现状与发展趋势

阐明了镁合金的阻尼机理及应变振幅、频率、温度对镁合金阻尼性能的影响.综述了当前改善镁合金阻尼性能的主要方法,如添加合金元素、控制变形工艺、热处理、控制晶粒尺寸和取向、添加增强相.指出通过添加新的增强相和合金元素,引入位错阻尼之外新的阻尼产生机制,解决阻尼性能与力学性能的矛盾,将是未来高性能阻尼镁合金材料研究的重要方向,而且,产品外形结构设计与阻尼性能的关系也是值得关注的一个新研究方向.     

Influence of Al Content on the Atmospheric Corrosion Behaviour of Magnesium-Aluminum Alloys

The influence of Al content on the Mg-Al alloys corrosion performance during sodium chloride induced at- mospheric corrosion has been studied. It was found that the corrosion rate of three Mg-Al alloys was accelerated with increasing Al content. The poor corrosion resistance was attributed to the galvanic coupling between the β phase and eutectic phase or α phase and the formation of porous corrosion products.     

Analytic EAM Model for the Thermodynamic Properties of the Disordered Solid Solution and Ordered Intermetallic Alloys of Iron Aluminides

1.IntroductionInthepastfewyearsthemeth0dsf0rempiricalandsemiempiricalcalculations0fpropertiesformet-alsandalloyshaveevolvedrapidly.Oneofthem0stsuccessfulmethodsistheembeddedatommethod(EAM)originallypresentedbyDawandBaskes[1J,butitsembeddedenergyandpairpotentialaregivenintheform0fsplinefunctions,suchanunanalyticalf0rmmakesthismodelverydifficulttobeappliedtoal1oys[2].J0hnsonhasdevelopedana1yticalEAMmode1sforfcc,bccandhcpmetal,[3~6j.Moreover,usingthefccanalyticalEAMmodel,J0hnsonhasca1culate…     

Effect of Solid Solution Supersaturation on Precipitation of γ′ in Rapidly Quenched Ni-Al Binary Alloys

The effect of solid solution supersaturation on the precipitation of γ′ in rapidly quenched Ni-Al binary alloys containing 11.6, 14.2 and 16.5 at. pct Al was investigated. The samples were solutioned at 1250°C, quenched in iced brine, and then analyzed by electron microscopy and XRD (X-ray diffraction) techniques. In Ni-11.6 at. pct Al alloy, ordering and phase separation took place simultaneously, resulting in a uniform distribution of γ′ . A transition from uniform to bimodal γ′ phase distribution occurred in the composition range between 14.2 and 16.5 at. pct Al. This transition was accompanied by changes in the morphology of γ′ precipitates. The microstructural observations were discussed in view of both kinetics and crystallographic considerations.