High Temperature Precipitation Hardening and Recrystallization of Al-Zr-Yb-Cr Alloys

采用透射电镜研究了Al-Zr-Yb-Cr合金中析出的弥散相的形态、结构和成分,采用硬度和金相观察对比了弥散相在500 ℃的析出硬化作用及其稳定性,以及对合金再结晶的抑制作用。结果表明：Al-Zr-Yb-Cr合金经500 ℃均匀化处理后析出了大量共格的、L12结构 (Al, Cr)3(Zr, Yb) 弥散相,弥散相均匀化处理400 h仍保持共格态,粒径维持在15~ 25 nm。其高温析出硬化及抑制铝基体再结晶作用优于Al3Zr和Al3(Zr,Yb)弥散相。     

退火制度对钎焊用热轧复合铝板组织与性能的影响

采用金相显微镜、扫描电镜、透射电镜、X射线衍射仪、拉伸试验机、硬度计等研究了4343/3003/4343铝合金轧制复合板在100~500℃退火15min~10h后的微观组织和力学性能。结果表明:芯层合金300℃退火1h后开始再结晶,370℃以上退火1h后已完全再结晶且伴随有弥散相析出,弥散相析出后通过钉扎晶界阻碍再结晶晶粒长大;1h退火时,随退火温度升高,芯层合金晶粒先增大后减小,复合板的拉伸强度与硬度先降低后升高;370℃退火时,随退火时间延长,芯层合金再结晶程度增加,晶粒缓慢长大,复合板的拉伸强度与硬度下降;复合板最佳退火工艺为370℃/1h。     

Effect of magnesium on dispersoid strengthening of Al—Mn—Mg—Si (3xxx) alloys

The effects of magnesium addition on the dispersoid precipitation as well as mechanical properties of 3xxx alloys were investigated. The microstructures in as-cast and heat-treated conditions were evaluated by optical microscopy and transmission electron microscopy. The results reveal that Mg has a strong influence on the distribution and volume fraction of dispersoids during precipitation heat treatment. The microhardness and yield strength at ambient temperature increase with increasing Mg content. The solid solution and dispersoid strengthening mechanisms of materials after heat treatment are quantitatively analyzed. Dispersoid strengthening for the alloys is the predominant strengthening mechanism after precipitation heat treatment. An analytical model is introduced to predict the evolution of ambient-temperature yield strength.     

软段对氨基磺酸盐型高固含量聚氨酯分散体性能的影响

以N-(2-氨基乙基)-2-氨基乙烷磺酸钠(AAS-Na)为亲水单体,以不同结构的多元醇、异佛尔酮二异氰酸酯(IPDI)、六亚甲基二异氰酸酯(HDI)和乙二胺(EDA)等为原料,采用丙酮法合成了固含量为50%的磺酸盐基聚氨酯分散体(PUD)。研究结果表明:PUD的ζ电位均低于-30mV,平均粒径在230～290nm之间,黏度均低于800mPa·s,呈现假塑性流体的特征;PUD胶膜的吸水率均低于10%,具有良好的耐水性能;PUD胶膜的结晶行为和力学性能受软段影响较大,起始分解温度为275℃,具有良好的热稳定性,能满足一般场合的使用要求。     

Temperature dependence of cyclic creep behavior of a Cu–SiO2 bicrystal with a [0 1 1] 20° twist boundary

Temperature dependence of cyclic creep behavior has been studied using a Cu bicrystal containing dispersed SiO₂ particles and a [0 1 1] 20° twist boundary. Failure occurred at shorter times with increasing temperature and stress amplitude. The fracture-mode of the bicrystals changed sharply from transgranular to intergranular at a certain critical stress amplitude. The brittle intergranular fracture that occurred below the critical stress amplitude caused discontinuous life shortening. The observed fracture-mode change at the critical stress amplitude is discussed in relation to grain-boundary sliding and grain-boundary cracking.     

The influence of manganese addition on mechanical properties of commercial Al‐4Mg casting alloys

The aim of this study was to investigate the mechanical properties of Al‐Mg‐Si alloys aged to peak hardness with different dispersoid volume fraction. It was found that the tensile strength increases with dispersoid content, for alloys having similar ductility. The effect of an increasingly triaxial stress state on a fracture strain above mentioned alloys were measured using a series of notched tensile specimens whose notch root radius of curvature was changed. The alloy ductility was found to increase with dispersoid content and root radius and to decrease with increased stress triaxiality. The fracture toughness of these alloys was determined as a function of dispersoid content and notch root radius of curvature. It was observed that the fracture toughness increased as the dispersoid content and the notch root radius increased. scanning electron microscope analysis of the fracture surfaces revealed that fracture mechanism was transgranular fracture with dimples formation. It is argued that optimum mechanical properties in these alloys can be achieved at about 0.5 % Mn content.     

含TiODS铁素体钢中弥散相再细化机制的研究

对含Ｔｉ的ＯＤＳ铁素体钢在机械合金化（ＭＡ）及随后热固实化过程中,弥散相显著再细化的条件和机制进行了研究。结果表明：在机械合金过程中,选用合理的工艺参数,所加入预加工粉中的弥散相－Ｙ２Ｏ３将首先分解成钇和氧原子,并能均匀地溶入基体中;在随后的热固实化过程中,将以一种更加细小和稳定的复合氧化物－Ｙ２Ｔｉ２Ｏ７的形式析出,并在钢的工体中分布更加均匀。     

AlMnFeSi合金退火过程中的微观组织及力学性能的演变

通过2种不同的均匀化热处理及随后的冷轧,使一种3xxx系模型合金获得不同尺寸和分布的弥散析出相,并使铝基体含有不同含量的Mn。系统研究不同均匀化热处理组织和冷轧变形量对退火过程中模型合金的回复与再结晶行为的影响。根据实验结果,绘制出弥散析出相和再结晶过程的相互作用时间-温度-转变曲线（TTT）。TTT曲线显示固溶体中Mn的含量和弥散析出相的颗粒密度对软化行为有强烈的影响。在再结晶退火过程中或再结晶退火之前析出的高密度、细小、弥散析出相显著阻碍软化过程,并形成粗大的再结晶组织。在没有细小、稠密的弥散相影响下的再结晶退火,可以获得均匀、细小的等轴晶。而且,弥散析出相对再结晶过程的阻碍作用取决于再结晶过程的持续时间和弥散析出相的数量。在持续时间长的再结晶过程中,细小、稠密的弥散相对再结晶有着强烈的影响,而在其他情况下影响则有限。不管再结晶过程中是否受到弥散相析出的影响,在再结晶退火之前已经存在于组织中的细小、稠密的弥散相（平均尺寸0.1μm）也会导致再结晶退火之后形成粗大的再结晶组织。     

聚酯丙烯酸杂化多元醇水分散体的制备

以间苯二甲酸-5-磺酸钠(5-SSIPA)与新戊二醇缩聚,制备亲水性中间体.用该中间体与羟基丙烯酸树脂、新戊二醇、三羟甲基丙烷和己二酸进一步缩聚,制得聚酯丙烯酸杂化树脂,加水分散后得其水分散体.研究了反应温度、羟基丙烯酸树脂的玻璃化温度及含量对杂化多元醇水分散体及其相应涂膜性能的影响.结果发现,适宜的杂化反应温度为22...     

C.I.颜料黄74制备原位聚合颜料分散体的染色性能研究

为了减少粘合剂对环境的污染,以合适的软单体和硬单体,过氧化苯甲酰为热引发剂,应用C.I.颜料黄74来制备原位聚合颜料分散体。通过原位聚合的方法使单体聚合并将C.I.颜料黄74固着在织物表面上。研究了超声波粉碎时间和次数、两类单体的配比、引发剂用量、颜料用量对摩擦色牢度的影响。结果表明,硬单体和软单体的比例为7∶3,引发...