Fe—40Al及其含Mn或Ti合金的Mossbauer谱

用Ｍｏｓｓｂａｕｅｒ谱研究了Ｂ２结构金属间化合物Ｆｅ－４０Ａｌ及其加Ｍｎ或Ｔｉ量分别为１，５，１０ａｔ．－％的合金．在室温下，Ｆｅ－４０Ａｌ及其合金的Ｍｏｓｓｂａｕｅｒ谱均接近单峰谱线，Ｆｅ原子无明显磁矩对加入第三组元的Ｆｅ—４０Ａｌ合金的Ｍｏｓｓｂａｕｅｒ谱用最小二乘法拟合为两条洛仑兹曲线之和，认为Ｍｎ原子既占据Ｆｅ原子位置，也占据Ａｌ原子位置；而Ｔｉ原子优先占据Ｆｅ原子位置，超过５ａｔ．－％时，才有少量Ｔｉ原子占据Ａｌ原子位置．     

代位原子在Fe3Al亚点阵中的占位与合金的塑性

采用中子衍射法测定了Ｃｒ、Ｍｏ、Ｔｉ、Ｎｉ、Ｍｎ、Ｓｉ等代位原子在ＤＯ３结构Ｆｅ３Ａｌ亚点阵中的原子占位，并从解离能角度探讨了原子对之间的相互作用及合金室温塑性的影响，结果表明：Ｃｒ、ＭＯ、Ｔｉ都占据了Ａｌ原子的次近邻位置，替代Ｆｅ原子；Ｎｉ、Ｍｎ占据Ａｌ原子的最近邻位置，（Ｓｉ＋Ａ）当量成分以内的Ｓｉ原子替代占据Ａｌ原子的位置，由于Ａｌ－Ｃｒ原子对的结合能低于Ｆｅ－Ａｌ，ＡＬ－Ｍｏ用Ａｌ－Ｔｉ对     

Al—5Fe—2Ni合金析出相的Mossbauer谱

用Ｍｏｓｓｂａｕｅｒ谱学和ＸＲＤ方法研究了快速凝固Ａｌ－５Ｆｅ－２Ｎｉ（原子百分数）合金的析出相，结果表明，析出相为三元化合物Ａｌ９ＦｅｘＮｉ２－ｘ（０〈ｘ〈２）属于单斜晶系，晶格参数ａ＝０．８５８ｎｍ，ｂ＝０．６３１ｎｍ，ｃ＝０．６２１ｎｍ，β＝９４．８，它的Ｍｏｓｓｂａｕｅｒ谱为一套双线，同质异能移位ＩＳ＝０．１２ｍｍ．ｓ＾－１，四极分别ＱＳ＝０．３２ｍｍ．ｓ＾－１，线宽Г＝０．２６ｍｍ．ｓ＾     

机械合金化合成Al—Ti系纳米过饱和固溶体

利用ＸＲＤ，ＴＥＭ，硬度试验研究了Ａｌ－Ｔｉ系的机械合金化（ＭＡ）过程．经４０ｈ球磨后，Ａｌ－１５ａｔ．－％Ｔｉ形成了Ａｌ（Ｔｉ）的过饱和固溶体，Ａｌ－１０ａｔ．－％Ｔｉ除形成Ａｌ（Ｔｉ）外，还产生了少量的ｆｃｃ结构的新相．而Ａｌ－５ａｔ．－％Ｔｉ在球磨１２０ｈ后也未能形成完全的Ａｌ（Ｔｉ），但有ｆｃｃ结构相的形成，这种特殊的固溶行为可以用溶质原子在纳米晶晶界快扩散解释     

STUDY FOR MECHANICAL ALLOYING OF Fe─M BY MOSSBAUER SPECTROSCOPY

将Ｆｅ－Ｍ（Ｍ＝Ｃ５ＳｉＯ２Ａｌ２Ｏ３）混合物在Ａｒ中高能球磨５６ｇ后测量Ｍｏｓｂａｕｅｒ谱，结果表明，（Ｆｅ）２－（ＳｉＯ２）１仍为Ｆｅ和ＳｉＯ２的机械混合物：（Ｆｅ）６－（Ｃ）３已完全合金化，生成两种Ｆｅ３Ｃ；（Ｆｅ）２－（Ａｌ２Ｏ３）１则成为Ｆｅ（７３％），尖晶石型的ＦｅＡｌ２Ｏ４）２２％），ｑｑｎｔＦｅ的团聚族（５％）和Ａｌ２Ｏ３的混合物。     

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。     

Fe—Mn和Fe—Mn—Si粉末混合物的机械合金化

对Ｆｅ－２４Ｍｎ，Ｆｅ－２４Ｍｎ－６Ｓｉ成分的粉末混合物进行了机械球磨，并对不同时间的球磨样品进行了Ｘ射线衍射（ＸＲＤ）和Ｍｏ¨ｓｂａｕｅｒ谱测量。结果表明，球磨使得Ｆｅ、Ｍｎ、Ｓｉ在原子尺度上发生了混合，形成了顺磁性、面心立方结构的Ｆｅ－２４Ｍｎ或Ｆｅ－２４Ｍｎ－６Ｓｉ纳米晶合金，这是Ｆｅ、Ｍｎ或Ｓｉ原子由颗粒表面到体内扩散的结果。球磨６７ｈ以后结构未发生变化，表明形成的是一种热力学亚稳结构，这个结果与Ｆｅ－Ｍｎ和Ｆｅ－Ｍｎ－Ｓｉ合金在室温下的相图结构明显不同。     

475℃ EMBRITTLEMENT DEVELOPMENT AND EMBRITTLING-INHIBITING MECHANISM BY YTTRIUM IN FeCrAl ALLOYS

经脆化动力学、内耗、ＴＥＭ和Ｍｏｓｓｂａｕｅｒ谱等研究表明：Ｆｅ－１５Ｃｒ－４Ａｌ和Ｆｅ－２５Ｃｒ－５Ａｌ合金的４７５℃脆化包括两种过程，碳化物在晶界析出损害界面结合，降低断裂应力、使塑性在时效０．２５ｈ后消失，时效温度从４００提高到６００℃时，发生过时效的时间从〉１０００ｈ缩短到约１ｈ，从α相均匀析出的富铬α‘相通过强化基体引起二次脆化，它与时效温度的关系有“Ｃ曲线”的特征，作用仅在４４０￣４７     

Al,Ti,Nb对铁基高温合金组织与性能的影响

研究了Ａｌ、Ｔｉ、Ｎｂ对Ｆｅ－２８Ｎｉ－１３Ｃｒ－１．２Ｗ－１．５Ｍｏ高温合金组织和性能的影响。随Ｔｉ含量增加，合金的强度提高，但η相的析出倾向及晶界相对于晶内的弱化效应增大，合金的塑性大幅度下降。Ａｌ和Ｎｂ都明显抑制η相析出，其含量过高时分别导致胞状γ’和Ｌａｖｅｓ相在晶界析出，胞状γ’相使晶界在中高温区严重脆化，Ｌａｖｅｓ相适量析出使晶界在中高温区得到有效强化。     

新型超微晶Fe81P12C3Si2.5Cu1Mo0.5合金结构与磁性的研究

在室温下，借助Ｍｏｓｓｂａｕｅｒ谱技术，研究非晶合金Ｆｅ８１Ｐ１２Ｃ３Ｓ２．０Ｃｕ１Ｍｏ０．５晶化过程中局域结构的变化。发现整个晶化由两个阶段组成；第一个阶段（３００－３６０℃）之间退火为α－Ｆｅ相的形核与长大阶段；第二个阶段主要为Ｆｅ３Ｐ相的形核与长大阶段。同时该合金在３６０℃退火获得最佳软磁性能。讨论了软磁性能与结构变化之间的关系。     

Phase separation in Fe-Mn (20–40 wt % Mn) alloys

The structural changes produced in the Fe-40Mn and Fe-20Mn alloys by long-term isothermal heat treatment at temperatures from 600 to 1200°C are studied using x-ray diffraction analysis, transmission electron microscopy, and hardness tests. The results provide evidence, direct for Fe-40Mn and indirect for Fe-20Mn, that the Fe-Mn solid solution in these alloys undergoes phase separation in the temperature range studied. The conclusion is made that the solid-solution region in the Fe-Mn system, as well as in a number of other systems, is in fact a phase-separation region.     

Processing of nanocrystalline FeAlX (X = Ni, Mn) intermetallics using a mechanical alloying and hot pressing techniques

Fe-40Al-40Ni-20 and Fe-40Al-40Mn-20 (all in at.%) intermetallics were mechanically alloyed for 40 h and followed by hot-pressing at 650°C under 450 MPa for 1 h. As resulted from the X-ray diffraction studies, the ordered B2 structure was formed in the Fe-40Al-40Ni-20 alloy while in the case of Fe-40Al-40Mn-20 alloy, the disordered Fe(Al) solid solution was observed. The chemically homogenous rounded particles of size of about 5 μm were identified using scanning analytical electron microscopy in alloys after 40 h of milling. TEM studies of milled powders revealed a nanostructure in both alloys with grain size of about 20 nm. The hot pressing process of milled powders allowed to obtain compacts with the density of about 87 and 89% of the theoretical one for Fe-40Al-40Mn-20 and Fe-40Al-40Ni-20 alloys, respectively. The micro-hardness measurements have shown that the alloy with the Ni addition possesses the hardness of about 1200 HV₂₀, whereas in the alloy with the Mn addition it is 1100 HV₂₀. The TEM investigations allowed to identify a nanocrystalline structure of compacts with a mean grain size below 50 nm, with B2 ordered structure in both alloys.     

Electrochemical and microstructural studies of sintered and sintered-plasma nitrided steel containing different alloying elements

The corrosion of sintered and sintered-plasma nitrided steels containing different alloying elements was evaluated through analysis of the potentiodynamic polarization curves of the samples at pH = 7, with 1.25 M KNO₃ as electrolyte. The Fe-3.0% Ni and Fe-0.1% C sintered alloys show better performance in relation to electrochemical corrosion, than sintered pure iron samples. In addition, Fe-4.0% Mn, Fe-1.5% Mo and Fe-1.5% Si alloys exhibited increased anodic current densities in relation to the pure iron sample. After the nitriding process the anodic current densities of all samples containing an alloying element were considerably diminished. The sintered-nitrided pure iron sample was the only nitrided part whose current density was higher than the current density of the non-nitrided sample.     

Nickel-free austenitic steels for cryogenic applications: The Fe-23% Mn-5% Al-0.2% C alloys

A study has been made of the influence of carbon and aluminium additions on the mechanical properties under uniaxial tensile loading and by Charpy V notch impact tests at room temperature and ?196°C on the Fe-24 % Mn alloys. It is concluded that the Fe-24 % Mn-5 % Al-0.2 % C appears as a new nickel-free iron-based alloy which is particularly interesting for cryogenic applications. In these alloys, both additions of carbon and aluminium contribute to the stability of the austenitic phase by suppressing the γ → ? martensitic transformation of the binary Fe-24 % Mn and to the solution hardening of the manganese-rich austenitic alloy.     

Creep of low-activated Fe-12Cr-20Mn-1W austenitic corrosion-resisting steel

Conclusions 1. Creep resistance of the Fe-12Cr-20Mn-1W steel, containing 0.1-0.26 wt. % C and also small additions of Ti, B, and P in the range 823–973 K is similar to the creep resistance of the Fe-Cr-NI steels of the 304 type, 800 alloy, and also the Fe-Cr-Mn-Ni steel of the ÉP838 type.2. An increase of the carbon content in the range 0.1–0.26 wt. % in the Fe-12Cr-20Mn-1W alloys slightly reduces the minimum creep rate 873 K and does not effect this parameter at 973 K.3. The efficiency of the effect of carbon on the minimum creep rate of the Fe-12Cr-20Mn-1W steels is evidently lower than the 800 alloy.Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 29, No. 2, pp. 81–85, March–April, 1993.     

Enhancement of mechanical properties of Al–Mg–Si alloys by means of manganese dispersoids

Abstract

The effects of Mn dispersoids on the enhancement of mechanical properties in Al–Mg–Si(–Mn) alloys have been studied to develop a new high Mn alloy which does not need an aging heat treatment after a shaping process (i.e. extrusion process). By adding Mn to Al–Mg–Si alloys, sphere- or rod shaped Mn dispersoids of a size ranging from 0·05 to 0·5 μm are formed by the use of proper heat treatments. The as extruded alloys containing 1·0 wt-%Mn are measured to have higher tensile properties with good ductility, as compared with those of the commercial Al alloy 6N01 (Al–0·69Mg–0·79Si–0·48Cu–0·27Zn–0·37Mn–0·3Cr– 0·11Ti, wt-%). These phenomena are obtained from the dispersion hardening effect and homogeneous deformation by Mn dispersoid particles acting as obstacles to dislocation movement. Comparing the fatigue crack growth behaviour between the high Mn alloys and the commercial 6N01 alloy in the as forged condition, high Mn alloys are shown to have higher fatigue crack growth resistance and show a more tortuous crack path. This result can be explained by the increasing energy absorption through crack deflections and tortuous crack paths by the Mn dispersoids.     

Improved surface properties of D2 steel by laser surface alloying

The wear and the high-temperature oxidation resistance of the D2 steel (Fe-1.5 C-12 Cr-0.95 Mo-0.9 V-0.3 Mn) were increased by laser surface alloying after coating the surface with SiC or Cr₃C₂ powder. The surface alloys exhibit two microstructures: hypoeutectic and hypereutectic, respectively, all containing iron solid solutions and iron-chromium carbides, (Fe,Cr)₇C₃. The oxidation resistance of these alloys was measured in isothermal and cyclic conditions, and was shown to increase with silicon or chromium additions, particularly due to the formation of a chromia scale with excellent behaviour during thermal shoks. The surface alloy obtained with Cr₃C₂ also has shown a better resistance to wear due to its hypereutectic microstructure.     

Effect of carbon on the paramagnetic-antiferromagnetic transition and gamma ->epsilon martensitic transformation of Fe-24Mn alloys

The effect of C content (0.014 similar to 0.39 wt pet) on the paramagnetic-antiferromagnetic transition and gamma --> epsilon martensitic transformation of Fe-24Mn alloys has been investigated by the resistivity, dilation, tensile properties measurement and microstructure examination. The results have shown that C decreases T-N, increases the thermal expansion coefficients both above and below the Tu, increases the resistivity above the TN and antiferromagnetic scattering resistivity below TN. It strongly depresses the gamma --> epsilon martensitic transformation and reduces the Ms of Fe-24Mn alloys. Moreover, it increases the lattice parameter of austenite, enhances the tensile ductility, but almost does not affect the tensile strength. With increasing C content from 0.014 to 0.19 wt pet, the yield strength of Fe-24Mn alloy decreases obviously arising from the decreasing of preexisting epsilon martensite, but it increases from 0.19 to 0.39 wt pet C due to the solution hardening of C.     

第四组元对机械合金化MgNiCu合金贮氢性能的影响

采用机械合金化方法由Ｍｇ，Ｎｉ和Ｃｕ单质粉末以及添加第四组元粉末按选定比例合成ＭｇＮｉＣｕ和ＭｇＮｉＣｕ－Ｍ５％贮氢材料，着重研究了分别添加不同的第四组元Ａｌ，Ｍｎ，Ｔｉ元素对不同球磨时间后ＭｇＮｉＣｕ合金贮氢性能的影响。结果表明，添加第四组元都不同程度地改善了ＭｇＮｉＣｕ俣金的初始活化条件；添加Ｍｎ能降低ＭｇＮｉＣｕ合金的吸放氢平台，显著改善其吸放氢动力学性质；添加Ｔｉ提高了ＭｇＮｉＣｕ合金的最     

钛粉末冶金研究进展(英文)

从第12届世界钛会可以看出,传统钛粉末冶金即冷压烧结在降低钛制品的制造成本和改进烧结钛制品的成分及显微组织方面已有了许多可喜的进展。结合第12届世界钛会有关钛粉末冶金方面的研究报告,主要从钛粉体烧结过程中氧和残留氯化物的去除和控制、使用氢化钛粉的优点、通过控制氢化钛粉烧结过程相变制备出具有超细(亚微米至几个微米)显微组织特征的高性能钛材料、合金元素含量高钛合金的烧结特点、微波辐射烧结钛及钛合金几个方面讨论了钛粉末冶金相关研究的最新进展。