Laves相Cr2Nb元素混合粉末的机械合金化

对Laves相Cr2Nb化学配比成分的元素混合粉末的机械合金化行为进行了研究.结果表明,在机械合金化过程中,Cr、Nb元素混合粉末首先变成复合粉末,复合粉末中的成分逐渐均匀并演变成过饱和固溶体.机械合金化40h后过饱和固溶体发生部分非晶化.粉末颗粒尺寸在机械合金化初期的5h内粗化,随后逐渐细化,50h后细至亚微米级.在50h的机械合金化过程中始终未发现Laves相Cr2Nb的合成.但15h的机械合金化粉末在900℃的较低温度下通过固相热反应合成出了Laves相Cr2Nb,而未球磨的原始粉末在此温度下未能合成.这说明机械合金化虽然没有直接合成出Laves相Cr2Nb,但产生了活化Laves相高温反应合成的效果,使合成反应温度显著降低.     

表面包覆法制备高固相含量SiC悬浮液的研究

本工作试图通过有机包覆的方法改善SiC粉在水中的表面胶体特性，制备高固相体积分数的SiC粉体悬浮液。以制备的悬浮液的固相体积分数为衡量标准，分别确定了APS和PAAM包覆过程最佳条件．（1）APS包覆：时间为5h，温度90℃，APS的质量分数为5％，此条件下可以制得固相体积分数为45％的SiC悬浮液；（2）PAAM包覆：时间为5h，温度30℃，AAM的质量分数为2％，在此条件下可以制得固相体积分数为50％的SiC悬浮液．     

1Cr21Ni5Ti钢管冷弯脆性问题研究

论文研究了热处理工艺对1Cr21Ni5Ti钢组织与性能’的影响,找到了材料冷弯脆性的原因,得到了如下结论：（1）材料产生脆性的原因是敏化处理时。相的析出,材料固溶后在650℃。900℃敏化处理时析出。相,导致塑性和韧性降低,并且在700℃敏化口相的析出量最大;（2）材料经固溶处理后在700℃保温10分钟时就有口相析出,20分钟达到最大析出量,导致塑性和韧性降低;（3）σ相在900℃～950℃之间开始溶解。已经产生。相的材料可以通过重新加热到950℃以上然后快速冷却来消除因σ相的析出而产生的脆性。     

ZnO-TiO2体系的固相合成与表征

以分析纯ZnO和TiO2粉体为原料,直接固相法制备钛酸锌粉体.利用X射线衍射（XRD）、扫描电镜（SEM）对粉体物相、形貌进行表征,采用热重-差热（TG-DTA）研究固相反应机理.结果表明：氧化物粉体最低反应温度为800℃,升高反应温度有利于Zn2TiO4相的生成,延长反应时间有利于六方相ZnTiO3生成.在800~900℃保温4 h获得平均粒径为0.3~0.5μm的球形钛酸锌粉体,该晶体生长过程为扩散机制控制,调整温度对产物形貌影响不大.     

固溶温度对超级双相不锈钢00Cr25Ni7M04N组织和性能的影响

试验和测试了900～1300℃固溶处理时双相不锈钢00Cr25Ni7Mo4N的相组成、冲击能AKV和硬度（HRC）值。试验结果表明，在900—1020℃固溶处理时，双相不锈钢中有16．97％～3．22％σ相析出，使钢的冲击能AKV值从1040—1250℃处理的224～280J降至3～44J。该双相不锈钢的热加工温度应大于1040℃，其最佳固溶处理温度为1040—1100℃。     

重载齿轮钢的高温性能

 通过Gleeble 1500D热模拟试验机高温拉伸试验,对比研究了17Cr2Ni2MoVNb和17Cr2Ni2Mo钢的高温性能。结果表明：因微合金元素V（0.1%,质量分数,下同）、Nb（0.036%）产生细晶强化及固溶强化,17Cr2Ni2MoVNb 钢的抗拉强度比17Cr2Ni2Mo钢稍高。在低N（0.0057%）含量的17Cr2Ni2MoVNb钢中,V和Nb对热塑性的危害很小。而高N（0.0130%）含量的17Cr2Ni2Mo钢在600～900 ℃及1050～1200 ℃温度区间塑性低于17Cr2Ni2MoVNb钢。N含量及相变温度不同导致第二期AlN析出量不同及铁素体先后析出,是造成两试验钢塑性差别的主要原因。     

0Cr19Ni15Mn5Mo2NbN铸钢晶界高温相析出及对力学性能的影响

利用光学显微镜、扫描电镜及透射电镜,结合Thermo-Calc热力学分析,研究了铌稳定化0Cr19Ni15Mn5Mo2NbN奥氏体不锈钢铸钢晶界处高温相析出行为及其对力学性能的影响。结果表明,0Cr19Ni15Mn5Mo2NbN钢晶界处存在Nb Cr(CN)、Nb(CN)2种大尺寸高温析出相,均为凝固末期液析形成。在铌含量确定条件下,这2种大尺寸晶界析出相在凝固末期的竞争析出行为受碳含量的影响。碳含量存在临界成分,碳含量低于临界成分时,Nb Cr(CN)首先液析形成;碳含量高于临界成分时,Nb(CN)首先液析形成。液析形成的NbCr(CN)热稳定性较高,1 050℃固溶处理无法使之完全溶入奥氏体。沿晶界分布的大尺寸析出相,对0Cr19Ni15Mn5Mo2NbN铸钢固溶热处理后的塑性及冲击韧性损害较大。     

1Cr13不锈冷轧带钢的质量控制

1生产工艺太钢1Crl3不锈冷轧带钢的工艺流程为：EF炉（50t）→铸锭（5．4t）→初轧开坯（140×1030）→热轧带炉卷轧机→电罩炉退火→热轧带钢酸洗→冷轧8辊轧机→冷带连续退火酸洗→平整2辊→成品精整。采用返回法冶炼，配碳量0．40％，出钢温度1620±10℃，固渣保护下铸5．4t扁锭，红送初轧厂开坯。1Cr13初轧均热温度1230℃，开轧温度≥1120℃，规格140mm×1030mm×Lmm，初轧坯热装低温退火770±10℃，钢坯全面砂轮修磨，修磨率3％。1Cr13热轧带钢工艺为：（1）连续式加热炉，均热温度1260℃，加热时间≥3h，炉内氧化性气氛。（2）高压…     

铌对00Crl2Ni不锈钢组织和性能的影响

分别冶炼了3种不同铌含量的00Crl2Ni不锈钢,用光学显微镜和透射电镜观察了热轧退火态的显微组织,测量了试验钢的拉伸性能和不同温度的冲击功。试验结果表明：铌的添加显著抑制了退火时铁素体再结晶的发生。未添加稳定化元素铌的钢中析出相为cr23Cr23C6,ω（Nb）为0．28％的试验钢中析出相为Nb（C,N）和Fe3Nb3C,ω（Nb）为0．49％的试验钢中析出相为Nb（C,N）和FezNb,而且其析出相总体积分数明显高于其他2种试验钢。铌的添加提高了试验钢的强度,降低了试验钢的塑性和韧性,ω（Nb）为0．49％的试验钢冲击功最低,但其韧脆转变温度也最低。     

过共析Ti-Cr合金的机械合金化

以钛、铬元素粉为原料研究了Ti-20％Cr(质量分数)和Ti-30％Cr 2种合金的MA规律。研究结果表明,在球磨初期的2 h内会发生钛的(011)主衍射峰强度迅速降低,(010)第二衍射峰强度提高并成为了最强峰,以及铬的衍射峰强度提高的现象。随着球磨时间的增加,钛和铬的X射线衍射峰都发生宽化、强度下降和衍射角左移减小。当球磨时间为30～40 h时,钛逐步非晶化。但是,在本试验条件下铬没有发生非晶化。MA的前10 h是粉末晶拉细化、晶格应变和合金化进行得最迅速的时期,经过该阶段球磨后铬的晶粒度可达20 nm;进一步球磨有利于获得过饱和固溶的合金粉末。2种合金在超过100 h的MA过程中均未发现在固相合成Laves相TiCr_2。根据试验结果制备纳米晶或者非晶过饱和固溶Ti-Cr合金粉末的合理球磨时间为30～40 h。     

Visual perception of mean relative phase and phase variability.

Perception of relative phase and phase variability may play a fundamental role in interlimb coordination. This study was designed to investigate the perception of relative phase and of phase variability and the stability of perception in each case. Observers judged the relative phasing of two circles rhythmically moving on a computer display. The circles moved from side to side, simulating movement in the frontoparallel plane, or increased and decreased in size, simulating movement in depth. Under each viewing condition, participants observed the same displays but were to judge either mean relative phase or phase variability. Phase variability interfered with the mean-relative-phase judgments, in particular when the mean relative phase was 0°. Judgments of phase variability varied as a function of mean relative phase. Furthermore, the stability of the judgments followed an asymmetric inverted U-shaped relation with mean relative phase, as predicted by the Haken-Kelso-Bunz model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ab initio phase determination and phase extension using non-crystallographic symmetry

Non-crystallographic symmetry (NCS) can be used to improve, extend or find ab initio phases to be associated with a set of observed structure amplitudes, resulting in an interpretable electron-density map. The simplest application is merely to improve the accuracy of the phases by cyclically averaging the electron density, Fourier back-transformation of the modified map, and recomputing a new map with the newly found phases. The first sophistication of this procedure is to phase extend, in successive small steps, the currently available phase information to higher resolution, where only observed amplitudes were previously available. A further sophistication is to initiate the phase extension from very low resolution where a simple geometric model, or an electron microscope image, would be consistent with the chosen resolution. A number of recent examples of virus structure determination exist where such ab initio phasing was successful. The ultimate ab initio phase determination would be to extend phases given only an estimate of the F(000) term.     

Nickel-aluminum-molybdenum phase equilibria

Recent work on alloys based on the Ni-Al-Mo system has brought to light several inconsistencies with published equilibrium phase diagrams for this system. Published diagrams have been based on theoretical computer models and on data gathered ostensibly before equilibrium was achieved, especially at temperatures below 1100 °C. The intent of this effort was to produce an experimentally validated ternary equilibrium phase diagram for the Ni-Al-Mo system. Specimens for this task were produced by both conventional casting and powder metallurgy techniques. The temperatures studied included 1260, 1171, 1093, 1038, and 927 °C (2300, 2140, 2000, 1900, and 1700 °F) for times up to 2500 hours. Phases were identified using an electron probe microanalyzer and X-ray diffraction. The results show significant deviations from the proposed phase diagrams published in the literature in the temperature range investigated. In particular, a class II four-phase equilibrium reaction γ + α cooling // heating γ′+ δ has been shown to occur at 1127 ± 2 °C (2060 ± 4 °F). Formerly NRC Senior Research Associate.     

Second phase dissolution

A detailed theoretical study was made of the dissolution of precipitates. The kinetic analyses of the atomic mechanisms included the concurrent effects of diffusion, interface reaction, and curvature, and considered the more complex problems of precipitate arrays and nondepleted matrices. The general formalism thus obtained was used to interpret the results of an experimental investigation of the technologically important problem of the dissolution of “reluctantly soluble” carbides in the Fe-C-V system. It was found that vanadium carbide (and iron carbide as well) were quite easily dissolved while complex alloy sulfides, silicates and oxides (possibly associated with the presence of vanadium) persisted, with little if any dissolution. Previous views of the reasons for poor hardenability were reevaluated in light of these results. Formerly with the Process Research Department, Scientific Research Staff, Ford Motor Co. This paper is based on an invited talk presented at a symposium on Homogenization of Alloys, sponsored by the IMD Heat Treatment Committee, and held on May 11, 1970, at the spring meeting of The Metallurgical Society of AIME, in Las Vegas, Nev.     

Co-Cr系相平衡的热力学计算和fcc相的磁性诱导相分离

Two-phase equilibria between the ferromagnetic fcc and the paramagnetic fcc phase from 800 ℃ to 900 ℃ in the Co-rich region have been detected by the diffusion couple technique. Two phase separation region of the fcc has been confirmed along the Curie temperature. The phase equilibria including the present results and the thermodynamic data of the Co-Cr system reported in the literature were analyzed on the basis of the thermodynamic evaluation. A set of thermodynarnic values for the liquid, fcc, hcp, bcc, sigma phases was obtained. The calculated phase equilibria were in good agreement with most of the experimental data.