Cu—Zn—Al—Mn合金高温时效时相变机制的研究

用示差扫描量热法、电阻测量和透射电子显微镜对Ｃｕ－Ｚｎ－Ａｌ－Ｍｎ合金高温时效的贝氏体相变进行了研究。结果表明，合金经高温时效，溶质原子首先析出，有利于降低层错能，随后由于切变引起在（１１１）面上形成大量层错，从而促进了贝氏体相变。     

Cu—Zn—Al—Mn合金贝氏体相变的位向关系

本文利用两相合成的选区电子衍射谱，介绍了确定平行晶面晶向指数的方法，借助于这一方法，本文测定了Ｃｕ－Ｚｎ－Ａｌ－Ｍｎ合金贝氏体与母相之间的位向关系。     

时效过程Cu－Zn－Al合金阻尼特性的研究

本文研究了热处理工艺对Ｃｕ－１４．１４Ｚｎ７．９７Ａｌ（ｗｔ％）合金自然时效阻尼特性的影响。合金的阻尼性能依赖于分级淬火参数Ｔ＿ｂ及ｔ＿ｂ且随时效时间的延长存在“峰效应”。Ｔ＿ｂ＝２００℃的分级淬火减少了时效过程中阻尼的损失，使合金处于稳定的高阻尼状态。Ｘ－ｒａｙ衍射分析表明，合金在自然时效时其结构有序度发生改变且有α相析出。合金阻尼特性的波动与空位等点缺陷和界面的相互作用及α相的析出有关。     

二元Al—Li合金时效相变的电阻法研究

通过电阻法研究了二元Ａｌ－２．０Ｌｉ（质量百分比）合金在１００℃，１９０℃时效时的电阻率随时效时间的变化，研究结果表明，二元Ａｌ－Ｌｉ合金固溶体分解过程中首先发现了短程有序化，然而通过均匀有序化形成δ′相，最后形成δ相。     

母相区时效和热循环对Cu－Zn－Al合金形状记忆特性的影响

采用一种精确测量形状记忆效应（ＳＭＥ）的方法研究了Ｃｕ－２６％Ｚｎ－４％Ａｌ合金８００℃淬火后在母相区１３０，１５０和１７０℃时效以及相变热循环过程ＳＭＥ变化的规律。淬火马氏体进入母相区时效初期回复率迅速升高，达到一个最大值以后随时间开始下降，显示出时效过程中马氏体稳定化效应的消除和贝氏体相变发展这两种机制所引起的相反效果。拘束条件下热循环引起回复率的衰减比起自由状态下要缓慢。这可能是应力的存在有利于诱发马氏体相变，使马氏体回复率显著提高所致。     

某高温合金高温时效稳定性研究

本文研究了某高温合金高温时效稳定性,分析了合金在高温长期时效过程中,γ?相的粗化遵循Ostwald熟化理论。     

β‘Cu—Zn合金中温区等温转变的研究

利用光学显微镜及透射电镜考察了β＇Ｃｕ－Ｚｎ合金中温区等温转变，发现其转变产物平衡相α１在ＴＴＴ图中具有各自独立的Ｃ曲线，在两Ｃ曲线交叉点温度以下的转变初期，可得到单相的亚稳贝氏体α１，而延长等温时间，α１将部分甚至完全退化为α，初期形成的α１内部具有完整的层错亚结构，其体转变激活能仅约为Ｚｎ扩散激活能的１／２。     

Ce－Y－TZP材料高温时效的强韧性研究

本文研究了不同烧结温度成分为１０ｍｏｌ％ＣｅＯ２－１ｍｏｌ％Ｙ２Ｏ３－ＺｒＯ２陶瓷材料（Ｃｅ－Ｙ－ＴＺＰ）经高温时效后力学性能的变化规律。结果表明，时效时间对材料的强度与韧性有较大影响，大约在２４ｈ左右，σ３ｂ、ＫＩＣ达到峰值。配合Ｘ射线分析，认为产生上述现象的原因主要是时效导致材料基体产生共格畸变所致。此外，断口形貌ＳＥＭ观察表明，断口局部出现了准解理断裂特征。     

弹性合金的高温长时效行为

本文对几种常用的弹性合金的高温长时效行为进行了研究,弄清了组织变化规律和高温稳定性能,找出了提高现有弹性合金的使用温度的途径.试验合金在高温长时效过程中,晶内球状γ'相长大;同时发生γ'→η相转变。大于850℃的高温时效可由基体直接折出η相.有些合金可能出现有害的 TCP 相。适当提高固溶温度;减少时效前的变形度;适当变动化学成分等,可提高合金高温稳定性,从而将使用温度提高.     

Enthalpy and Temperature of the Titanium Alpha-Beta Phase Transformation

The specific enthalpy and the temperature of the titanium - phase transformation were measured by a pulse-heating system operating in the millisecond time regime. The measurement technique is based on self-heating of a tube-shaped specimen from room temperature to the beta phase of titanium. A comparison between the measured phase transition temperature during heating and cooling of the specimen shows a difference of approximately 20 K. The temperature measured during the heating period is higher than the value obtained from the cooling cycle of the specimen. For the evaluation of the specific enthalpy of the alpha-beta transformation, the specific enthalpy versus temperature function of the beta phase of the heating period was extrapolated to the transition temperature obtained from the cooling cycle (1152 K). A total of 12 measurements on 3 tube-shaped specimens was made, an average value of 89.9 kJkg^–1 was obtained for the specific enthalpy of the transformation. The reproducibility of the measured specific enthalpy at the beginning and at the end of the transformation was 0.5%. The reproducibility of the phase transformation enthalpy as difference between the beginning and the end was 3%. The extended measurement uncertainty (at a confidence level of 95%) is estimated to be ±6% for the specific enthalpy of the transformation and ±6 K for the transformation temperature.     

Isothermal Aging Kinetics in CuZnAl Shape Memory Alloy

Isothermal aging behaviours of a CuZnAl shape memory alloy have been investigated by means ofdilatometry.The length of the specimens during isothermal aging from 190 to 280℃ increases withthe aging time at each temperature.The isothermal aging kinetics fits in Avrami equation and thetime exponent n decreases with the increase in aging temperature.The apparent activation energyfor the isothermal aging process was measured to be 109.0kJ/mol,which is about equal to that of arelaxation internal friction peak at about 200℃ (f≈1 Hz) in the alloy.     

高温老化对HMX基炸药爆速的影响

为掌握高温老化对HMX基炸药爆速影响的规律,选择粘合剂不同的两种HMX基炸药进行高温老化试验。通过测量药柱尺寸,计算炸药的密度,采用电雷管起爆测试方法获得了试样的爆速。结果表明:高温老化时间对炸药的密度影响不同,老化8天是两种炸药密度变化的分界点,超过8天,试样的密度发生较大变化;两种炸药的爆速随老化时间下降显著,但H-2炸药的爆速始终高于H-1炸药。     

中温自反应钎焊铝蜂窝芯耐高温老化性能分析

采用微小力学测试系统对经过高温老化的中温自反应精密钎焊铝蜂窝芯接头进行拉剪性能测试,并利用扫描电子显微镜及能谱仪对其进行显微组织形貌观察和成分分析,研究接头组织及成分变化与其耐高温老化性能的关系。结果表明:利用1060铝箔和铝合金复合钎焊板所制备的铝蜂窝芯在200℃高温老化12,24,36h后拉剪强度与未老化时相比均无明显下降,且接头的薄弱部分为靠近钎焊接头的母材部分。铝蜂窝芯接头组织形貌及成分分析显示,高温老化对钎缝组织中金属Zn,Sn含量影响不大且无新的化合物相形成;钎缝组织及成分不发生明显变化是蜂窝芯接头耐高温老化的主要原因。     

GH2027铁基高温合金的第二相研究

运用电子显微分析和波谱分析等方法对ＧＨ２０２７合金的第二相进行了研究，结果表明，合金晶界相主要是片状Ｍ６Ｃ和薄膜状Ｍ２３Ｃ６，经波纹图样测得其错配度约为３％，晶内Ｍ６Ｃ和Ｍ２３     

铸态AZ31镁合金热压缩过程中的再结晶行为

利用Gleeble-1500在温度200～500℃和应变速率0.001～1s-1范围内对铸态AZ31镁合金进行热压缩实验,并对动态再结晶行为进行研究。基于温度-应变速率的变化规律(Zener-Hollomon参数,Z参数),分析了形变温度和应变速率对铸态AZ31镁合金组织结构的影响规律。结果表明:动态再结晶发生后,再结晶晶粒尺寸随着形变温度的降低而减小。随着Z值的增加,动态再结晶作用增强,形变组织细化。为了便于工程应用的参考,给出了相应的热加工三维图。     

Ta合金高温防护涂层研究

使用料浆熔烧工艺在Ta-10W合金表面制备了Si-Cr-Ti-W系统的硅化物涂层。分析认为,涂层由二硅化物和硅基共熔体组成。在结构上由外表面保护膜、主体层以及界面内层三部分构成。保护膜在高温下阻止氧向基本的浸渗,减少与硅的化学反应,使主体层保持较高的硅含量。内层有助于释放涂层积聚的内应力,保持良好的界面结合。高温性能测试结果表明,在1800℃高温下抗氧化寿命超过2.5h,使该温度到室温的热循环达80次。     

Phase Transformation and Thermal Stability of Aged Ti-Ni-Hf High Temperature Shape Memory Alloys

The use of Ni-rich TiNiHf alloys as high temperature shape memory alloys （SMAs） through aging has been presented. For Ni-rich Ti80-xNixHf20 alloys, their phase transformation temperatures are averagely increased more than 100 K by aging at 823 K for 2 h. Especially for the alloys with Ni-content of 50.4 at. pct and 50.6 at. pct, their martensitic transformation start temperatures （Ms） are more than 473 K after aging. TEM observation confirmed that some fine particles precipitate from the matrix during aging. The aged Ni-rich TiNiHf SMAs show the better thermal stability of phase transformation temperatures than the solutiontreated TiNiHf alloys. The fine particles precipitated during aging should be responsible for the increase of phase transformation temperatures and its high stability.     

高温高压下立方氮化硼晶体的生长机制

在４．５－５．０ＧＰａ，１５００－１８００℃范围内，对在Ｌｉ基复合氮化物或氮硼化物和催化体系中以及其中添加Ｌｉ８ＳｉＮ４后合成ｃＢＮ进行了研究。探讨了ｃＢＮ晶体的表面构造和生长机制，研究了由六方氮化硼向立方氮化硼转变过程中硅的存在在行为。本实验中合成的立方氮化硼为具有光泽的棕色透明单晶。     

Phase Transformation and Deformation Mechanism of Ti_3Al-base Alloy

The phase transformation and deformationmechanism of the alloy based on composition Ti_3Alwith addition of Nb,V,Mo have been studied by useof transmission electron microscopy (TEM).It hasbeen shown that the orientation relationship ofα_2 phase transformed from β phase is:(0001)α_2//(l10)β,[1210]α_2//[111]β.The present dislocationslip systems in α_2 phase are (1100)[0001] and(1100)<1120>.There also exist α_2 twins whichhave new twin relationship and the twin plane is(2021).