超临界二氧化碳GAS重结晶制备HMX微细颗粒的研究

比较了ＣＯ２对丙酮，环己酮，二甲基亚砜体积膨胀的影响和ＨＭＸ在上述三种溶剂中ＧＡＳ重结晶时的析晶率。以丙酮为溶剂用ＣＯ２ＧＡＳ重结晶，在一定的条件下可获得２－１３μｇβ－型ＨＭＸ微细颗粒。     

连铸温度范围内钢的蠕变性能

研究了钢在低应变速率下的热塑性,得出了描述应变速率与热塑性关系的模型。研究结果表明,低应变速率下的热塑性与蠕变密切相关。     

掺杂钨丝的再结晶

本文利用金相显微镜、扫描电镜、透射电镜和X射线衍射技术研究了掺杂钨丝的微观组织变化,同时对不同温度下退火处理的样品进行了抗拉强度、显微硬度和室温内耗的测定。结果表明,掺杂钨丝退火时可分为三个阶段:回复、一次再结晶和二次再结晶。文中提出了亚晶聚合是一次再结晶的主要形核机制的观点。     

AZ31镁合金无缝管挤压动态再结晶数值模拟研究

通过热压缩实验得出温度在300~450℃,应变率为0.01~1 s-1时的应力-应变曲线,建立了AZ31镁合金的动态再结晶模型。该模型用于AZ31镁合金无缝管挤压过程中动态再结晶过程的数值模拟,并通过金相观察得以实验验证。结果表明,在挤压速度确定的情况下,挤压温度对动态再结晶分数的影响最为明显。随着挤压温度的升高,动态再结晶体积分数明显增大。预测的动态再结晶体积分数与实验结果吻合。     

Forming mechanism of refined granular crystalline of Cu70Ni30 alloy by undercooled solidification

Moth glass fluxing and cyclic superheating techniques were adopted to effectively uudercool the Cu₇₀Ni₃₀ alloy in vacuum. Within the undercooling range of 21 K to 270 K, the microstructure evolution ol the alloy was investigated. When the inell was undercooled to △T > △T', (210 K) , the grain refinement took place abruptly, liascd on the observation of the solidified microstructure, the rnierocheinieal-analysis and the calculated results with UCT model, it is found that the secondary grain refinement mechanism consists of two stages. The dendrite is, firstly, broken into hag-ments owing to the stress caused by uneven shrinking during rapid solidilication, then the fragments, under the driving force of surface and strain energies, merge through the migration of l>ouinlaries, i. c. recryslallization, thus leading to the formation of secondary granular-crystalline .     

N-甲基-2-对二甲氨基苯乙烯吡啶碘盐的合成及分析

研究了N-甲基-2-对二甲氨基苯乙烯吡淀碘盐的合成及分离方法,通过可见吸收光谱、MS谱、HNMR谱分析,证实了其结构和理论预期的一致性。     

热形变工艺参数对珠光体转变动力学的影响

本文研究了热形变工艺参数对40Cr 钢珠光体转变动力学的影响.研究结果表明,晶粒大小,形变温度和形变量对珠光体转变动力学都有影响,从而影响了动态再结晶过程.对生产各种形状和尺寸的模锻件来说,可通过调节热形变工艺参数来控制高温形变组织,从而达到控制室温组织与性能的目的.     

Microstructural evolution during ultra-rapid annealing of severely deformed low-carbon steel: strain,temperature, and heating rate effects

An interaction between ferrite recrystallization and austenite transformation in low-carbon steel occurs when recrystallization is delayed until the intercritical temperature range by employing high heating rate. The kinetics of recrystallization and transformation is affected by high heating rate and such an interaction. In this study, different levels of strain are applied to low-carbon steel using a severe plastic deformation method. Then, ultra-rapid annealing is performed at different heating rates of 200–1100℃/s and peak temperatures of near critical temperature. Five regimes are proposed to investigate the effects of heating rate, strain, and temperature on the interaction between recrystallization and transformation. The microstructural evolution of severely deformed low-carbon steel after ultra-rapid annealing is investigated based on the proposed regimes. Regarding the intensity and start temperature of the interaction, different microstructures consisting of ferrite and pearlite/martensite are formed. It is found that when the interaction is strong, the microstructure is refined because of the high kinetics of transformation and recrystallization. Moreover, strain shifts an interaction zone to a relatively higher heating rate. Therefore, severely deformed steel should be heated at relatively higher heating rates for it to undergo a strong interaction.     

从混合二元酸中分离提纯戊二酸

结合企业的生产,本研究中采用重结晶的方法对混合二元酸结片中的戊二酸进行提纯,探索了料水比、结晶温度、结晶时间等结晶条件对戊二酸纯度和回收率的影响,在不引入新杂质的条件下,得到戊二酸的纯度大于99.0%.     

冷轧低合金高强钢再结晶和析出行为研究

利用热模拟试验机研究了冷轧低合金高强钢的再结晶动力学规律,并基于JMAK方程建立了再结晶动力学模型,为退火过程中铁素体再结晶和析出行为的控制提供了理论依据.结果表明,随退火温度升高,铁素体达到完全再结晶时所用时间大大缩短;冷轧压下量相同时,初始贝氏体组织具有更高的位错密度和储存能;80℃/s快速加热条件下,回复和再结晶过程相应同步提前,且再结晶发生前的剩余变形储能增大,从而使铁素体再结晶快速完成.同时新工艺下实验钢析出粒子尺寸更均匀,体积分数更高,析出强化贡献更明显.