B_2型FeAl金属间化合物的制备及性能研究进展

对B2型FeAl合金的制备和性能研究现状进行了综述和分析.FeAl合金的制备工艺主要包括熔铸法和粉末冶金两种.FeAl合金的室温韧性可以通过合金化、细化晶粒、热处理和复合韧化等方法改善.合金化对提高FeAl高温强度和蠕变抗力有效,通过引入第二相粒子实现沉淀强化和弥散强化的效果最好,合金的使用温度有望提高到700℃以上.     

Fe元素对ZA27合金显微组织和力学性能的影响

在ZA27合金中添加0.5%~2%的Fe元素,利用金相、扫描电镜(SEM)、能谱分析(EDS)、X射线扫描(XRD)、拉伸实验等测试手段,研究Fe含量对ZA27合金显微组织和力学性能的影响。结果表明:不同Fe含量的ZA27合金基体组织均由富铝的α相和富锌的η相组成。Fe元素以FeAl3金属间化合物的形式分布于基体中。随Fe含量增加,FeAl3的含量增多、尺寸增大。FeAl3能阻碍晶界迁移,起到细化枝晶的作用。研究还发现,室温下,随Fe含量增加,ZA27的强度和伸长率均降低;150℃高温下,Fe含量为1.5%左右的ZA27合金抗拉强度达192.75MPa,比未加Fe元素的ZA27合金提高约54.4%,伸长率达15.65%,从而获得兼具高强度和高塑性的高温ZA27合金。     

过热处理对Al-1.1％Fe合金固态组织的影响

采用差示扫描暑热分析仪(DSC),将Al-1.1?合金熔体过热至液相线以上不同温度进行冷却,研究其凝固时过冷度及固态组织中FeAl3相尺寸的变化,发现过冷度及固态组织中FeAl3,相尺寸随熔体过热温度的提高而变化的曲线在某一高温(约900℃)时存在明显转折,低于900℃,随着过热温度的提高,其过冷度急剧增大,固态组织中FeAl3,相显著细化,而高于这一温度后,上述变化则非常缓慢.     

纳米结构FeAl合金无序和热恢复过程中的组织、力学和磁性能

本文研究了经球研磨和退火Fe-40Al%B2合金的微观组织、力学和磁性能。它的无序过程的特征是便合金产生硬化和顺磁－铁磁转变,主要决定于晶粒细化和反位缺陷的形成,再有序过程使纳米晶合金连续软化和恢复到顺磁态,基本上由反位缺陷的湮没控制。微机组织、力学和磁性能之间的关联使磁性测量成了一个很好的研究FeAl纳米合金微结构和力学状态的非破坏工具。     

低温烧结制备超细晶FeAl合金及性能的研究

Fe、Al混合粉末经高能球磨后,在560～620℃进行低温烧结。结果表明,低温烧结温度对合金组织有明显的影响,经过12h球磨,在620℃烧结4h,可以得到超细晶FeAl金属间化合物。SEM、AFM和XRD的分析结果表明,晶粒均匀,呈等轴状,大小约为30nm左右。超细晶FeAl金属间化合物的显微硬度较低,断裂为韧窝断口,呈现塑性变形特征。     

TiAl合金形成热模拟研究

调整了MAEAM模型中的电子密度参数比,并以相图为基础考虑每个成分比的相结构,应用改进分析型嵌人原子方法(MAEAM)计算了TiAI合金形成热.计算结果与Miedema理论结果进行了比较,二者的变化趋势一致.为了说明计算方法的可靠性,用同样的方法计算了NiAl合金和FeAl合金形成热.模拟结果与实验结果和第一性原理计算结果相一致.     

添加镀镍碳纳米管对注射成形FeAl显微组织与性能的影响

为研究碳纳米管(CNTs)对FeAl金属间化合物的增强增韧作用,采用机械合金化FeAl粉末和注射成形工艺制备出CNTs-FeAl复合材料.研究了化学镀镍处理对CNTs分散性和高温稳定性的影响.结果表明,表面镀镍可以显著改善CNTs在FeAl粉末中的分散性,并有利于减轻CNTs与FeAl基体的高温反应,从而显著提高了注射成形FeAl的抗拉性能.在烧结温度1 230℃、保温105min条件下,制备出了抗拉强度和伸长率分别为430 MPa和4.0%的CNTs-FeAl复合材料.     

FeAl合金的高能球磨穆斯堡尔谱研究

采用真空电孤炉熔炼制备Fe50Al50合金，Fe50Al50合金的穆斯堡尔谱线为单峰，这说明完全有序B2-FeAl合金是无磁性的。将有序B2-FeAl合金进行球磨100、120h后，再测量该粉末的穆斯堡尔谱，得到的是展宽的多峰谱线。这表明，球磨后合金样品发生了有序-无序转变，可以通过无序化来提高FeAl合金的磁矩。     

几种铝合金的焊合特性

通过H13钢热浸铝试验研究了纯铝、YL112合金及YL102合金熔体的压铸焊合特性,结果表明:H13模具钢在纯铝熔体中热浸形成了Fe2Al5、FeAl3金属间化合物相层,热浸YL112、YL102合金熔体形成了FeSiAl3、Fe2Al5金属间化合物相层,YL112、YL102合金熔体中的Si元素能够抑制热浸组织中金属间化合物层的快速生长,减弱熔体与模具钢间的相互作用,使YL112、YL102合金与压铸模具间的焊合倾向降低。     

B2—FeAl合金基本性能及间隙缺陷的理论研究

本文基于EAM势,利用分子动力学方法研究B2-FeAl金属间化合物的基本物理性能及合金体相中含B原子缺陷的性质。研究结果表明:采用EAM势来研究FeAl合金是可靠的;对于点缺陷的形成,合金中B取代Al位的缺陷形成能最低,形成Al反位缺陷最容易,其次是Fe反位缺陷,最后是间隙缺陷。     

弹簧钢的合金化研究

通用合金弹簧钢是用途最广、最重要的弹簧材料。分析了标准合金弹簧钢的合金化特点及常用合金系列。标准合金弹簧钢使用的合金元素不够广泛，合金系列比较简单，未能充分利用多元合金化的效应。分析和研究了弹簧钢合金化的最新发展趋势。其特点是在更广泛和深入地研究合金元素作用、合金系列及合金化理论的基础上，扩大了合金元素的使用范围，特别是使用了很多以前未曾用过的微量合金元素，发展了大量多元（甚至七元或更多）合金系列，充分利用合金元素的复合合金化效果，明显改善了弹簧钢的性能     

稀土在耐热镁合金中的应用

本文介绍了稀土对耐热镁合金发展的影响 ,概括了稀土耐热镁合金的发展历史及现状。初步讨论了稀土元素对镁合金耐热性能的影响机理。对稀土耐热镁合金的研制开发、应用前景进行了展望。     

高密度钨合金及其在军事工业中的应用

综述了高密度钨合金的特性,简要地介绍了国内高密度钨合金研究与生产状况,以及中南工业大学粉末冶金研究所在这方面所作的一些工作。同时介绍了高密度钨合金在军事工业中的主要应用及对今后的展望。     

Investigation on the Wear Properties of Primary Si Modified Al–20Si Alloy

In the present study, Al?C20Si alloy has been modified by Cu?C13P master alloy to obtain Al?C20Si?C0.1P alloy. The wear properties of Al?C20Si?C0.1P alloy have been investigated and compared with that of Al?C20Si alloy. The microstructure of Al?C20Si?C0.1P alloy consisted of primary and eutectic silicon distributed in the Al matrix. The size of primary Si is much smaller than that observed in Al?C20Si alloy. Wear tests have been conducted over a wide range of loads and sliding velocities. It has been observed that the wear rates of Al?C20Si?C0.1P alloy are lower than that of Al?C20Si alloy. The coefficient of friction is more or less constant in both the alloys but is low in Al?C20Si?C0.1P alloy. The better wear resistance of Al?C20Si?C0.1P alloy is discussed in the light of its modified microstructure evolved during solidification.     

形状记忆合金在航空航天领域的应用与进展

叙述了形状记忆合金的功能特性,并介绍了NiTi形状记忆合金在航空航天领域的应用及其进展。     

Flow pattern and alloy dissolution during tapping of steel furnaces

Abstract

Alloying of steel during tapping from BOFs and EAFs has been studied by computational fluid dynamics in two-dimensional axisymmetric models of two ladles. The flow patterns and particle trajectories have been computed for six different levels of steel in the tapping ladle, five different alloy sizes, two alloy injection points, and three types of bulk alloy (FeMn, SiMn, and FeSi75). Based on the fluid dynamics in the ladle and a definition of good alloying practice, conclusions with regard to alloy sizing and timing of alloy addition have been established. The computational results support findings in plant tests, which show the benefit of using small sized alloys. Furthermore, a method that allows us to estimate the optimum feeding rate for alloy additions during steelplant operation has been developed. Results from full scale tests in steelplants are shown.     

Relationships between process parameters and temperature field of roll casting for wide sheet made of AZ61 magnesium alloy: Finite element method

In recent years, wide sheet made of AZ61 wrought magnesium alloys has been widely studied and applied in industry. Thin roll-casting technology for the new wrought magnesium alloy can provide acceptable quality wide and thin sheet made of AZ61 magnesium alloy. To study the influences of roll-casting process parameters on temperature field for wide and thin sheet made of AZ61 magnesium alloy plates, some simplification and assumptions have been done by characteristics of magnesium alloy. Two-dimensional FEM model for roll-casting has been established along casting direction. Simulations of temperature fields of the plates have been done by using finite element analysis ANSYS software. A series of researches on the temperature distributions under different process parameters (pouring temperature, heat-transfer coefficients and casting speeds) have been done. The simulation results and the literature about the casting process of the relevant theory are the same. The simulation results show that the process parameters of rapid-casting process for AZ61 magnesium alloy are mutual influenced on the temperature fields of wide sheet made of AZ61 magnesium alloy.     

Sliding wear response of a zinc-based alloy compared to a copper-based alloy

In the present investigation, an attempt has been made to study the wear response of a zinc-based alloy at different sliding speeds and pressures. The wear behavior of the zinc-based alloy has been compared to that of a conventionally used copper-based alloy against an EN24 steel disc. Operative wear mechanisms have also been discussed through the examination of wear surfaces, subsurface regions, and debris particles. The results obtained revealed that the wear response of the zinc-based alloy is much better than the conventionally used copper-based alloy at all the speeds; the latter suffered from “material chipping off,” leading to its higher wear rates. The wear characteristics of the specimens have been explained on the basis of their specific microstructural features.     

ZTi-3B铸造钛合金材料的组织和性能

介绍了ZTi-3B合金在不同状态下的组织、室温及高温力学性能,并对精铸热处理态的室温力学性能进行了分析。合金经试验及实际应用证明:性能稳定、工艺性良好。     

Effect of Plastic Deformation on Magnetic Properties of Fe-40% Ni-2% Mn Austenitic Alloy

The effects of plastic deformation on the magnetic properties of austenite structure in an Fe-40% Ni-2 % Mn alloy is investigated by using Mossbauer spectroscopy and Differential Scanning Calorimetry （DSC） techniques The morphology of the alloy has been obtained by using Scanning Electron Microscopy （SEM）. The magnetic behaviour of austenite state is ferromagnetic. After plastic deformation, a mixed magnetic structure including both paramagnet- ic and ferromagnetic states has been obtained at the room temperature. The volume fraction changes, the effective hyperfine fields of the ferromagnetic austenite phase and isomery shift values have also been determined by Mossbauer spectroscopy. The Curie point （Tc） and the Neel temperature （TN） have been investigated by means of DSC system for non-deformed and deformed Fe-Ni-Mn alloy. The plastic deformation of the alloy reduces the TN and enhances the paramagnetic character of austenitic Fe-Ni-Mn alloy.