形变氮化08F钢冲击断口的分形研究

利用垂直截面法测量了０８Ｆ钢经不同形变氮化复合后冲击断裂表面的分形维数。结果表明，材料的冲击能Ａ和沿裂纹扩展方向剖面Ｋｏｃｈ曲线的分形维数Ｄ地均随表变量的增而增加。分形维维数Ｄ与ｌｎＡ之间呈正变化的关系，且满足下列关系式：ｌｎＡｋ＝４９．４３ＫＦ－５１．４４。     

FRACTURE BEHAVIOUR AND FRACTURE TOUGHNESS OF Al-2.5Li-1.3Cu-0.9Mg-0.13Zr ALLOY

The fracture mechanism for Al-2.5Li-1.3Cu-0.9Mg-0.13Zr alloy is quite different fromundergone various regimes of heat treatment.With the decrease of solution temperature andthe increase of aging temperature,the intergranular delamination and necking fracture on thefracture surface increase and the shearing facture decreases.Thus,the toughness of the alloymay be much improved.     

SiC涂层碳纤维增强铝复合丝的机械性能及其界面特性

研究了不同热处理温度对碳化硅涂层碳纤维增强铝复合丝的拉伸强度影响,结果表明:500℃热处理2h及550℃热处理1h后使复合丝的拉伸强度提高,600℃以上的热处理都使复合丝的拉伸强度下降,通过测量从复合丝中分离出来的纤维强度,表明碳化硅涂层对碳纤维具有良好的保护作用,用电子探针及能量损失谱分析了C/Al界面的稳定性。     

定向凝固的界面形态转变SCIEI

采用透明模型丁二腈—1.1％乙醇合金,从界面形态发展的时间相关性的角度,对平-胞转变和胞-枝转变进行了实验研究。实验结果表明,忽视界面形态发展的时间相关性,会导致过高估计平-胞转变速度和胞-枝转变速度。提出了一种确定平-胞转变条件的渐进线方法。确定了胞-枝转变速度随温度梯度变化的规律。     

Au-Si非晶态合金的恒温相变

用电阻测定及X射线衍射法研究了共晶成分Au-Si合金快速凝固箔带在等温时效时的相变过程,提出了由非晶态至平衡态的四阶段转变顺序,分析了各亚稳相的结构和电子浓度特征,说明在等温时效过程中亦可生成Hume-Rothery电子化合物及尺寸因素化合物。     

EFFECT OF Ce ON PREFERRED ORIENTATION OF GRAIN IN OXIDE SCALE ON Fe-15Cr ALLOY

用倒极图法研究了含0.3％Ce对Fe-Cr合金在高温下氧化膜(Cr_2O_3)择优取向的作用。加Ce的主要取向为(10110)⊥、(1014)⊥,(1126)⊥;不加的主要取向为(1014)⊥,(1126)⊥,(0112)⊥。 实验证明,Ce富聚于氧化膜和基体(α-Fe)的界面,起着增强和保持氧化膜择优取向的作用,从而改善合金的抗氧化性能。     

DETERMINATION OF σ-OR M_(23)C_6-PHASE IN STAINLESS STEEL BY STEP POTENTIAL ETCHING CURRENT METHOD

本文介绍一种新的相分析法——阶跃电位浸蚀电流法,并用它实现了化学难以分离的σ与M_(2■)C_6分别测定.方法简单快速,可以得到钢中析出物的含量、成分和形貌的情报.并且基于一种新的电极过程模型导出了定量分析公式,它已被实验证实.     

MOCVD Growth of Doped GaAs/AlGaAs Quantum Heterostructures

The influences of growth techniques of AP-MOCVD GaAs/AlGaAs silicon-doped multi-quantum wells(MQWs), heterostructure bipolar transistors (HBTs), double barrier resonant tunneling diodes(DBRTDs) ontheir structures and performances were studied. Continuously grown MQWs, that is, no growth interruption atthe heterointerfaces, shown blue-shifted, narrower and stronger photoluminescence(PL) compared withinterruptedly grown ones.TEM examination of the interrupted interfaces revealed a bright line correspondingto the compositional fluctuation and impurity adsorption, and indicated noncommutative structures ofAlGaAs/GaAs and GaAs/AlGaAs interfaces. High performance HBTs and DBRTDs were obtained bycontinuously grown method while growth interruption caused performance degradation. It was concluded thatgrowth interruption may cause accumulation of residua1 impurities in the ambient as well as compositionalfluctuation while continuous growth at very low growth rates can overcome such problems.     

TEM IMAGING TECHNIQUE

This imaging technique is used for approximate interpretation of TEM data including ungrounded loopsource and grounded line source soundings.Loop source data can be collected as central-loop soundings or asout-of-loop soundings with a short or long offset configuration.The imaging method is based on the same princi-ple as that employed by Fullager(1989),with apparent resistivities computed directly from time-derivative data,db/d,and then associated with depths according to image theory.     

BREAKAGE MECHANISM OF TUNGSTEN BASED ALLOY BLOCK FOR ELECTRO-HEAT UPSETTING

The breakage mechanism of W-Ni-Fe alloy in the process of electro-heat upsetting studied both theoretically and experimetnally, and also the behaviors of crack formation and propagation were analysed. Alloy suffers from corrosion and thermal-mechanical fatigue mutual function. Simultaneously, the practical ways to improve the anvil life was discussed.