Al含量对Fe－Al无序固溶体性能的影响

本文应用余氏理论，对不同Ａｌ含量的富Ｆｅ区Ｆｅ－Ａｌ无序固溶体进行价电子结构计算和分析，从理论上探讨了Ａｌ含量对合金晶格常数、原子磁矩、塑性以及晶体内原子状态的影响。研究发现，Ｆｅ－Ａｌ无序固溶体的晶格常数、原子磁矩和塑性随含Ａｌ量的变化，是由于合金中Ｆｅ、Ａｌ原子之间相互作用导致原子状态发生变化的结果。     

Al含量对Fe—Al无序固溶体性能的影响

本文应用余氏理论，对不同Ａｌ含量的富Ｆｅ区Ｆｅ－Ａｌ无序固溶体进行价电子结构计算和分析，从理论上探讨了Ａｌ含量合金晶格常数、原子磁矩、塑性以及晶体内原子状态的影响。研究发现，Ｆｅ－Ａｌ无序固溶体的晶格常数、原子磁矩和塑性随含Ａｌ的变化，是由于合金中Ｆｅ，Ａｌ原子之间相互作用导致原子状态发生变化的结果。     

B2型Fe—Al合金键结构及脆性的电子理论研究

应用余氏理论，对不同Ａｌ含量的富Ｆｅ区Ｆｅ－Ａｌ无序固溶体进行价电子结构计算和分析，从理论上探讨了Ａｌ含量对合金晶格常数，原子磁矩，塑性以及晶内原子状态的，研究发现，Ｆｅ－Ａｌ无序固溶体的晶格常数，原子磁矩和塑性随含Ａｌ量的变化，是由于合金中Ｆｅ，Ａｌ原子之间相互作用导致原子状态发生变化的结果。     

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．     

Fe—40La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Ｆ原子位置，也占据Ａｌ原子位置；而Ｔｉ原子优先占据了Ｆｅ原子位置，超过５ａｔ．－％     

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     

化学键性质机械合金化过程中非晶形成能力的影响

研究了Ｂ２型金属间化合物ＦｅＡｌ和ＦｅＴｉ的机械合金化过程，发现的相同的试验条件下，ＦｅＡｌ形成化学无序的固溶体，ＦｅＴｉ形成结构无序的非晶态，此现象可用ＦｅＡｌ的化学键为金属－离子混俣键，而ＦｅＴｉ的化学键为金属－共价－离子混合键来解释。     

室温应变速率及Al含量对FeAl合金拉伸性能的影响

研究了初始应变速率在１．３９×１０＾４￣６．９５×１０＾－１ｓ＾－１范围内Ｆｅ－４０Ａｌ的室温拉伸性能。结果发现，应变速率对ＦｅＡｌ合金室温下的断裂延伸率屈服强度和抗拉强度均有不同程度的影响，其中对断裂延伸率的影响最为显著。应变速率对ＦｅＡｌ合金力学性能的影响程度还与Ａｌ含量有关，Ｆｅ－３６．５Ａｌ较Ｆｅ－４０Ａｌ合金受应变速率的影响更大，研究结果还表明，Ａｌ含量还影响着ＦｅＡｌ合金拉伸断口中穿晶     

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。     

机械合金化Fe－Al－（Si）合金组织结构的研究

通过Ｘ射线和透射电镜等分析手段，研究了机械合金化（ＭＡ）对Ｆｅ_（７１．３）Ａｌ_（２８．４）（ＣｅＯ_２）_（０．３）和Ｆｅ_（７３．３）Ａｌ_（９．８）Ｓｉ_（１６．６）（ｃｅＯ_２）_（０．３_成分合金组织结构的影响。实验结果表明：随着ＭＡ时间的增加，α－Ｆｅ固溶体形成。当ＭＡ至７２ｈ后，α－Ｆｅ固溶体相对稳定化，其点阵常数、有效晶粒直径不再变化。     

The detection of a strong influence of composition variations on low-temperature magnetic ordering in nearly stoichiometric Fe–V–Al alloys

The magnetic state of Fe–V–Al alloys with nearly stoichiometric (Fe₂VAl) compositions varying with respect both to aluminum and transition elements was studied. The effect of strong qualitative change in the magnetic properties induced by small variations of the composition was observed for the first time and analyzed. The key result is the detection of ferromagnetic ordering with a relatively high (~50 K) Curie temperature in an alloy with V atoms substituted in the lattice by Al atoms and the Fe content corresponding to the stoichiometric composition.     

Magnetism and solid solution effects in NiAl (40% Al) alloys

The solid solution effects of ternary additions of transition elements in intermetallic Ni–40% Al were investigated by both experimental studies and theoretical calculations. Co solute atoms when sitting at Ni sublattice sites do not affect the lattice parameter and hardening behavior of Ni–40Al. On the other hand, Fe, Mn, and Cr solutes, which are mainly on Al sublattice sites, substantially expand the lattice parameter and produce an unusual solid solution softening effect. First-principles calculations predict that these solute atoms with large unfilled d-band electrons develop large magnetic moments and effectively expand the lattice parameter when occupying Al sublattice sites. The theoretical predictions were verified by both electron loss-energy spectroscopy (EELS) analyses and magnetic susceptibility measurements. The observed softening behavior can be explained quantitatively by the replacement of Ni anti-site defects (potent hardeners) by Fe, Mn, and Cr anti-site defects with smaller atom size mismatch between solute and Al atoms. This study has led to the identification of magnetic interaction as an important physical parameter affecting the solid solution hardening in intermetallic alloys containing transition elements.     

Annealing effects on the structural and magnetic properties of Fe–Al silica nanocomposites prepared by sequential ion implantation

The nanostructural and magnetic properties of FeAl–SiO₂ granular solids prepared by sequential ion implantation have been investigated as a function of the annealing atmosphere (either oxidizing or reducing) and implantation order. Nanoscopic particles with a bcc structure were found in both as-implanted samples. In the sample Al–Fe prepared by implanting first the Al ions and later the Fe ions, the lattice parameter indicates the presence of practically pure iron nanoparticles. On the other hand, in sample Fe–Al with the implantation order inverted, the lattice parameter is consistent with the presence of an iron rich iron–silicon alloy. The magnetic data confirm the presence of the pure Fe and the Fe–Si alloy in the as-implanted samples and the absence of FeAl intermetallic compounds. The annealing in Ar/H₂ promotes the growth of the clusters and increases the Si content in the particles in both samples. In Fe–Al sample, this induces a disorder–order phase transition from the disordered Fe–Si solid solution to the Fe₃Si phase and the coprecipitation of the ordered FeSi phase. The magnetic moment increases after the annealing in Ar/H₂ due to the incorporation of the iron atoms dispersed in the matrix and to the higher crystalline order. The annealing in air is responsible essentially of the growth of the Fe–Si clusters in both samples. On the other hand, in sample Al–Fe the oxygen interacts with the pure iron clusters by promoting the Fe₂O₃ formation.     

Effect of Al content on stacking fault energy in austenitic Fe–Mn–Al–C alloys

Effect of Al content on the stacking fault energy (SFE) was investigated in the austenitic Fe–25Mn–(1.16–9.77)Al–0.68C (at%) alloys by X-ray diffraction line profile analysis and thermodynamic estimation, and was discussed on the basis of anomaly in shear modulus caused by the antiferromagnetic transition. The experimental results show that the stacking fault probability decreases with increasing Al content, the observed SFE increases linearly when Al content is lower than 6.27 at%, and markedly as it is more than 6.27 at%. The thermodynamic estimation indicates that the non-magnetic component of SFE increases faster than the observed one with increasing Al content in the antiferromagnetic state, and both are almost equal in the paramagnetic state. The magnetic order increases SFE in the antiferromagnetic state, and the magnetic component of SFE depends on the average magnetic moment and Néel temperature. The increases in the localized magnetic moment and the decrease in the Néel temperature are caused by the addition of Al atoms into the austenitic Fe–Mn alloys and are accompanied by the anomaly in shear modulus, which affects SFE in the antiferromagnetic state. The anomalous drop in shear modulus leads to the inconsistency for the variations of the observed SFE and non-magnetic component with Al content in the antiferromagnetic state.     

镁铝尖晶石固溶体成分对TiN析出行为的影响

通过2205双相不锈钢渣-钢反应平衡实验,得到不同炉渣配比下的MgO-Al_2O_3二元系固溶体夹杂,当反应达到平衡后,向钢中添加了0.05%的Ti,进而得到了"MgO-Al_2O_3固溶体+TiN"的复合夹杂。试样经水淬后,通过电镜分析夹杂物,然后采用10%的草酸进行电解,与不加Ti的铸态组织δ铁素体晶粒形貌、尺寸进行了对比。实验结果发现:TiN析出量随MgO-Al_2O_3固溶体中Al_2O_3比例的增加而增加,铸态δ铁素体晶粒可得到明显细化,实验结果发现富MgO的MgO-Al_2O_3固溶体以及MgO·Al_2O_3析出TiN很少,δ铁素体细化效果不明显。通过热力学计算、异质形核理论以及实验结果证明,MgO-Al_2O_3二元系固溶体夹杂物成分由炉渣成分及钢中Mg、Al活度共同决定,MgO-Al_2O_3固溶体中Al_2O_3含量增加,使MgO·Al_2O_3晶格发生畸变,这与点阵中存在着空位密切相关。由于空位富集,使得点阵常数e不均匀,也由于空位改变晶格场,引起O2-的移动或转移,形成缺位尖晶石固溶体。晶格的能量状态发生变化促进了Ti原子和N原子在MgO-Al_2O_3夹杂物表面析出。     

Bonding Characteristics of the Intermetallic Compound Al_3Ti+Cr

Based on our structural model and a tight-binding Hamiltonian the eIectronic structure has been calculated by use of a recursion method (RM) for two models of the tetragonal DO22 and the cubic Ll2 crystal structures in Al3Ti+Cr for contrast, from which bonding characteristics have been discussed. The results for the interaction energy (IE) show that Cr prefers to replacing Al site. Cr partly replacing Al can change the IE between the atoms and make the constriction of lattice constant c and the elongation of lattice constant a for the DO22 and thereby may induce the change of crystal structure from DO22 to L12. The results for bond order integral (BOI) and IE between the atoms also show that the strong (110) directional Cr-Ti bondings are existed.Thus, Al3Ti-base intermetallic compounds with addition of the Cr atom still remain brittle.     

Phase transformations in Ni + Al and Ni + Al + Cr mixtures during mechanochemical synthesis and subsequent heating

Mechanochemical processing of elemental mixtures with the compositions Ni₇₅Al₂₅, Ni₇₀Al₂₅Cr₅, and Ni₇₅Al₂₀Cr₅ (5 at % Cr in the mixtures instead of the equivalent amount of Ni or Al) leads to the formation of nanocrystalline nickel-based solid solutions (crystallite size in the range ? 7?C12 nm). Comparison of experimentally determined lattice parameters of the solid solutions with Vegard??s law values and with the lattice parameters evaluated using the Bozzolo-Ferrante rule, which takes into account the bulk moduli of constituent elements, suggests that the atoms in the solid solutions are bonded more strongly. Heating the synthesized ternary solid solutions in a calorimeter to 1000°C leads to the formation of an ordered ?á?-phase (L1₂). Analysis of the relative intensity ratio of superlattice and fundamental reflections indicates that the Cr atoms always reside in the Al sublattice, independent of the composition of the starting mixture. When 5 at % Cr is incorporated instead of Ni, the chromium atoms force out aluminum from the Al sublattice, and the Ni deficiency in the Ni sublattice is compensated by the Al atoms. The ordered phases remain nanocrystalline (crystallite size in the range ? 40?C70 nm).     

Structural,optical and magnetic properties of Cu doped CdSe powders prepared by solid state reaction method

Cu doped CdSe powders were synthesized by solid state reaction method and studied the effect of Cu doping concentration on structural, optical and magnetic properties of the prepared samples. From XRD study it was found that the lattice constant increased with increase of Cu doping concentration. A clear blue shift was observed in the samples from optical studies. From the magnetic measurements, it was found that the samples were room temperature ferromagnetic in nature and strength of magnetic moment increased with increase of doping concentration. These synthesized powders are dilute magnetic semiconductors and are very promising candidates for ‘Spintronic’ device applications.     

激光刻蚀工艺对Al2O3-ZrO2固溶度和结晶度的影响

利用X射线衍射，X射线吸收精细结构谱和高分辨电镜研究了激光刻蚀工艺对Al2O3-ZrO2固溶度和结晶度的影响．结果表明，Al2O3在ZrO2中的固溶度越大，ZrO2晶体结构无序度越大．样品室的空气压力越大，粉体中无定形相的含量越大．无定形ZrO2中存在短程有序-长程无序结构Zr-O-Zr（Al）．同Al2O3-ZrO2固溶体相比，无定形ZrO2具有更短的Zr-O和Zr-Zr（Al）原子间距离和更大的无序度．