Cu-1.4Ni-1.2Co-0.6Si合金的析出与再结晶的交互行为

通过对施加30%~70%的冷变形量的Cu-1.4Ni-1.2Co-0.6Si合金时效过程中的显微硬度及导电率规律分析和透射电镜观察,发现固溶合金时效前冷变形可加速时效初期第二相析出,导电率得以快速上升。如合金经过30%形变400℃时效1 h后导电率可达43%IACS,而固溶后直接时效为40.7%IACS。经过冷轧-时效后,沿位错分布着许多细小的析出相,使位错在时效过程中运动困难,同时合金内形成了高密度的位错,析出相弥散细小分布在基体中,故可以获得较高的显微硬度,如经30%形变于400℃时效2 h其显微硬度可达HV223,而未加形变直接时效合金的显微硬度为HV202。形变析出与再结晶过程中再结晶时间tR和时效析出时间tP取决于形变量和时效制度,在一定的形变量和较高的时效温度的条件下,合金内晶粒易发生再结晶。合金70%变形500℃时效2 h,由于基体中产生高密度的位错,会降低再结晶激活能QR,故在显微组织中发现了亚晶粒,从而降低了合金的强化效果,此时其显微硬度为HV206。该合金在450℃时效处理时组织转变主要有两种:一是第二相弥散分布在铜基体中;另一种是析出与再结晶交互作用而产生的不连续析出。     

稀土元素镧对Cu-15Ni-8Sn合金组织及性能的影响

采用金相显微镜、扫描电镜和X射线衍射分析研究添加稀土元素镧(La)及其添加量对Cu-15Ni-8Sn合金组织及性能的影响。研究结果表明,添加微量La元素可以细化枝晶组织,改善合金的枝晶偏析,并且随着La添加量增加,改善效果越明显。La可与Ni或Sn反应形成LaNiSn相或La₅Sn₃相,并且随着La添加量增加,析出相逐渐由LaNiSn相向La₅Sn₃相转变。添加0.8%(质量分数,下同)La可以有效抑制形成不连续沉淀,分布在晶界上的La₅Sn₃相可以占据不连续沉淀的形核位点,分布在晶体内的La₅Sn₃相可以抑制不连续沉淀前沿界面的移动,共同作用抑制了Cu-15Ni-8Sn-0.8La合金时效过程中不连续沉淀的形成。此外,Cu-15Ni-8Sn-0.8La合金在450℃时效30 min获得HV硬度峰值为324。     

抑制Cu-Ni-Mn合金晶界择优析出的方法

本文利用金相观察法,研究了时效温度、冷变形和合金元素对Cu-20Ni-20Mn合金时效时晶界择优析出的影响,制定抑制该合金晶界择优析出的方法。结果表明;时效前的冷变形能有效地抑制晶界择优析出,高温时效(450℃)和添加合金元素钛也取得良好的结果。     

固溶时效工艺对Cu-Ni-Si合金组织和性能的影响

用扫描电镜(SEM)、硬度计、涡流电导率测量仪和万能试验机测试分别测量了在850 ～950℃固溶温度及400 ～ 500℃时效不同时间下对Cu-1.5 Ni-0.6Si合金硬度及电导率性能的影响,用金相显微镜观察不同固溶温度下合金的组织.并对合金拉伸形貌断口进行了分析.探讨了合金的强化机理.结果表明:时效前随着固溶温度的升高,材料的硬度及电导率均随之下降,但电导率下降的幅度很小.随着固溶温度的增加,其再结晶程度越来越高,到900℃时组织已是完全再结晶组织,温度继续升高,晶粒会发生长大.时效析出为Cu-1.5 Ni-0.6Si合金的主要强化手段.Cu-1.5Ni-0.6Si固溶后经不同温度时效后,时效初期硬度和电导率快速上升.随后硬度到达峰值后缓慢下降,而电导率继续上升.经过900℃×1h水淬+450℃×2h空冷处理后,合金得到良好的综合性能;其抗拉强度为780.7 MPa,伸长率为15.1％,电导率为40.2％ IACS.     

Cu-15Ni-10Mn合金形变热处理研究

研究了冷轧加工率与再结晶温度对Cu-15Ni-10Mn合金组织性能的影响以及形变时效工艺对合金力学性能的影响,详细说明了冷轧加工率与再结晶温度的匹配关系和合金形变时效强化机理.实验结果表明：冷轧加工率的增加,可降低Cu-15Ni-10Mn合金发生完全再结晶的温度;通过形变时效处理,合金内部析出MnNi粒子并阻碍晶界和位错运动,可显著提升合金力学性能;合金经加工率为70％的冷轧后,进行400℃保温48h的时效处理,硬度达394HV,抗拉强度大于1000MPa.     

添加Ag对Cu-15Ni-8Sn 合金组织及性能的影响

通过对不同Ag含量的Cu-15Ni-8Sn合金铸态、固溶态和时效态的微观组织进行分析,研究了Ag添加对 Cu-15Ni-8Sn 合金组织及性能的影响。结果表明,适量Ag元素的添加能够减少铸态Cu-15Ni-8Sn合金 的枝晶间距,抑制显微偏析,改善合金的铸态组织。此外,当Ag含量为0.2 wt.%~ 0.5 wt.% 时,可有效抑制时效过程中不连续沉淀相的析出,从而改善合金的力学性能。但是,当Ag添加量大于等于0.5 wt.% 时,对不连续沉淀的抑制效果减弱。     

形变热处理对Cu-6.5Ni-1Al-1Si-0.15Mg-0.15Ce合金微观组织及性能的影响

设计并制备 Cu-6.5Ni-1Al-1Si-0.15Mg-0.15Ce(wt.%)合金。采用光学显微镜(OM)、扫描电镜(SEM)、能谱分析和透射电镜(TEM)等测试手段研究合金形变热处理过程中微观组织及性能的变化。合金铸态组织为典型的枝晶组织,铸锭经过920℃热轧后,枝晶组织显著消除。合金的适宜固溶处理制度为960℃/4 h。该合金固溶处理后的冷变形对合金最终性能有很大影响。冷变形程度越大,合金达到硬度峰值的时间越短,硬度峰值和电导率越高。时效温度越高,时效析出过程越快。960℃固溶4 h后冷轧50%,450℃时效2 h硬度峰值可达300.8 HV,电导率20.6%IACS,抗拉强度963.9 MPa,屈服强度950.1 MPa。合金在时效过程中析出纳米级粒子为δ-Ni2Si,其与基体的位相关系为：Cuδ[001][001], Cuδ(110)(010), Cuδ(110)(100)。     

固溶处理对Cu-3.2Ni-0.75Si-0.3Zn合金组织及性能的影响

研究了Cu-3.2Ni-0.75Si-0.3Zn合金时效前固溶温度和时间对该合金硬度及电导率的影响,并且分析了不同固溶条件之后时效对Cu-3.2Ni-0.75Si-0.3Zn合金性能的影响。结果表明:时效前固溶温度的升高,材料的电导率先较快下降,之后又回升,而硬度呈下降的趋势,当固溶温度到达925℃时,硬度下降缓慢;随着固溶温度的增加,其再结晶程度越来越高,到900℃时组织已是完全再结晶组织,温度继续升高,晶粒会发生长大;通过扫描电镜及能谱分析仪观察900℃固溶后的试样,发现只有少量析出相存在。而相对于固溶温度,固溶时间对合金性能的影响不明显。在不同固溶制度下,合金试样经冷变形和时效后,其电导率随固溶温度的升高先降后升,而抗拉强度和延伸率随固溶温度的升高会先升高后下降,固溶温度为925℃时试样的抗拉强度到达峰值,延伸率则在850℃时达到峰值。与其他固溶处理制度相比,合金在900℃×60 min固溶处理,经60%的冷变形,450℃×4 h时效处理后,可得到较好的综合性能。此时,合金抗拉强度达到762 MPa,延伸率为6.1%,电导率为32.5%IACS。     

时效与冷变形对Cu-Ni-Si合金微观组织和性能的影响

应用新型生产线固溶处理工艺对Cu-2.8Ni-0.7Si-0.1Mg合金进行处理,研究了时效温度、时效时间和时效前不同变形量对Cu-2.8Ni-0.7Si-0.1Mg合金微观组织和性能的影响.结果表明,合金在450℃时效时,第二相呈细小弥散状态分布在基体上,能获得较好的综合性能,在450℃时效4 h时,其导电率和显微硬度分别可达38.13%IACS和212.6HV.经过对选区电子衍射花样的标定,析出相为Ni<,2>Si.合金经冷轧变形后内部出现大量的晶体缺陷,能在时效初期促进第二相的析出,使合金具有更好的综合性能,合金经60%变形后在450℃时效1 h后其导电率和显微硬度分别可达38.78%IACS和232.1 HV.继续升高时效温度或延长时效时间会引起第二相长大而导致显微硬度的升降.通过对生产线固溶和常规实验室固溶处理的合金进行性能比较,生产线固溶态合金的显微硬度时效后低于常规固溶处理合金,这可能是由生产线固溶时的不彻底性所导致.     

粉末冶金Cu-15Ni-8Sn合金时效组织的演变行为

对粉末冶金Cu-15Ni-8Sn合金进行热挤压、固溶处理后,研究400℃时效不同时间对合金力学性能及其组织的影响。结果表明:随时效时间延长,Cu-15Ni-8Sn合金的抗拉强度先升高后降低,伸长率先降低后升高,合金断裂方式表现为由沿晶断裂为主向穿晶断裂为主转变。合金抗拉强度在400℃时效1.5 h时获得最大值918MPa。综合考虑合金的强度和韧性,400℃的最佳时效时间为2 h。借助扫描电子显微镜和透射电子显微镜研究合金在400℃时效不同时间(1~3 h)的组织结构变化及其对合金强度和塑性的影响,结果表明:在欠时效阶段,合金组织在富Sn区出现了有序排列的介稳态DO22相,基体的FCC结构开始向DO22有序化结构转变,合金强度大幅提升。而在峰时效阶段,DO22向L12转变,合金强度继续增加,随片层状不连续析出组织开始由晶界向晶内生长,合金强度下降。在过时效阶段,DO22进一步向L12转变,并且片层状不连续析出组织开始大肆侵蚀基体调幅组织,导致合金强度降低,塑性提高。在时效后期,调幅组织被片层状组织大幅侵蚀,出现片层状组织粗化并断裂的现象,粒状γ相(DO3)不断生成,由于这一过程需要更大的浓度起伏而进行得非常缓慢,合金组织仍以大量片层结构为主,因而合金强度和塑性变化不明显。     

The psychologist with 20/20 vision.

Examines some of the visionary issues relevant to consulting psychology beyond the millennium. Issues related to globalization, challenging and empowered work groups, the spectrum of multidimensional and innovative technology, and what the health professional may likely face between now and the 1st quarter of the 21st century are addressed. Clinical algorithms for health care delivery, 21st-century skills, and the paradigm shifts that psychologists and other administrators and clinicians must accommodate during this transition period are explored. A series of futuristic trends and their import for further study are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microstructural Evolution of Brazed CP-Ti Using the Clad Ti-20Zr-20Cu-20Ni Foil

Microstructural evolution of the clad Ti-20Zr-20Cu-20Ni foil brazed CP-Ti alloy has been investigated. For the specimen furnace brazed below 1143?K (870???C), the joint is dominated by coarse eutectic and fine eutectoid structures. Increasing the brazing temperature above 1163?K (890???C) results in disappearance of coarse eutectic structure, and the joint is mainly comprised of a fine eutectoid of (Ti,Zr)₂Ni, Ti₂Cu, Ti₂Ni, and ??-Ti.     

Wetting of some hard alloys by Melchior MNMts20-20

Conclusions A study was made of the density and surface tension of manganese Melchior MNMts20-20 at 1260–1280°C. Experimental angles of contact and works of adhesion were obtained for manganese Melchior on hard alloys containing titanium and tungsten carbides. It was established that the surface tension and density of liquid manganese Melchior are 1360 ergs/cm² and 8.35 g/cm³, respectively. The work of adhesion for the systems investigated is > 2000 ergs/cm² at angles of contact of < 90°. It was found that the wetting of T5K10, T15K6, and T30K4 hard alloys by Melchior MNMts20-20 is less effective than that of VK type alloys. As a general rule, the wetting ability of hard alloys decreases with increase in their titanium carbide content. The results obtained are fully in accord with conclusions concerning the wetting of the carbides based on their heats of formation. It was confirmed that the higher the heat of formation of a carbide, the poorer is its wetting ability.Translated from Poroshkovaya Metallurgiya, No. 9, (141), pp. 51–55, September, 1974.     

Phenomenology of precipitation in copper-20 pct nickel-20 pct manganese

The precipitation phenomena in the alloy copper-20 pct nickel-20 pct manganese have been investigated. Utilizing transmission electron microscopy as the principal tool; the effects of aging temperature and time as well as prior cold work were studied. For all aging temperatures the reaction products are the solute depleted fcc solid solution and an ordered structure with fct symmetry. Three aging temperatures characterized by different precipitate morphologies were studied. At 350°C discontinuous precipitation is the predominant mode of decomposition. Precipitate colonies nucleate at grain and twin boundaries and eventually grow through the entire structure. Microtwinning of the colony matrix accompanies the precipitation reaction. At 450°C both grain boundary nucleated discontinuous precipitates and fine periodic homogeneous arrays are observed in the absence of cold work. The fine periodic arrays coarsen and eventually form nuclei for the ordered fct phase. The coarsening of the periodic arrays prohibits the growth of the discontinuous precipitate early in the process, so only a small volume fraction of discontinuous precipitate is formed at the grain boundaries. Aging subsequent to cold work results in ordered, fct precipitates heterogeneously nucleated on dislocations. At 500°C no precipitate is observed in the absence of cold work. When aging is preceded by cold work, the ordered fct phase appears as heterogeneously nucleated Widmanstatten laths. No grain boundary nucleated colonies are observed at this temperature.     

Effects of Cold-Rolling Reduction on Microstructure,Thickness, Surface Roughness of AS20/20 and on Bending Toughness of AS20/20-Coated Press-Hardened Steel

The tailor-rolling blanks based on Al–Si-coated press-hardened steel (PHS) have attracted much attention along with the development of lightweight vehicles. The properties of Al–Si-coated PHS with single surface weight of 20 g m⁻² change after cold-rolling and then austenitization, which are little studied. Herein, the effects of cold-rolling reduction ratio on the microstructure, thickness, and roughness of AS20/20 coatings, and on the bending toughness of AS20/20-coated PHS, are explored. The overall continuity of the coatings is unchanged as the reduction ratio increases. When the reduction ratio is 30% or above, rapid diffusion channels are formed at the cracks of Al-filled intermetallic compound layer. Meanwhile, the thickness and surface roughness of the coatings are stable and do not decrease. After austenitization, the coatings are structurally consistent with the increase of the reduction ratio. When the reduction ratio is 30% and above, the thickness and surface roughness of the coatings are stable and do not decrease. The rapid diffusion channels lead to an increment in the proportion of FeAl phase to above 96% after austenitization, which makes the bending angle further increase. The bending angle is enlarged by 44% when the reduction ratio is 50%.     

20CrMnSiA中板材热处理工艺探讨

对20CrMnSiA热轧板材进行热处理工艺试验,以确定合理的热处理制度.结果表明20CrMnSiA板材在不要求脱碳层的前提下,成品热处理可采用700℃×6h在罩式退火炉中进行;否则采用700℃×(30～40)min在辊底式退火炉中进行.     

The crystallization of a Pd60Ti20Si20 metallic glass

The kinetics and mechanism of crystallization have been followed in a Pd₆₀Ti₂₀Si₂₀ metallic glass by means of a combination of experimental techniques. As quenched alloys contain a variable population of crystals and/or nuclei. Oxide islands were found mostly on the dull (wheel-side) surface of the ribbon, favouring partial crystallization around 710 K. The glass transition temperature, T_g, is manifest in DSC and low-frequency internal friction measurements from heating rates of 1 K/min upwards, prior to the main crystallization event (761 and 772 K at 20 K/min heating rate, respectively). Isothermal crystallization in the temperature range from 739.0 to 758.7 K occurred in two steps because of a different population of quenched-in nuclei in various parts of the ribbon. A Johnson-Mehl-Avrami analysis of the DSC isothermal output gave an Avrami exponent of 3, indicating growth on preexisting nuclei, as shown by microscopy observations. The activation energy and the preexponential factor for growth are very high: 566 ± 20 kJ/mol and 10³⁶ms⁻¹ respectively. This finding is discussed with reference to analogous data for diffusion in metallic glasses.     

利盟迎来20岁生日

利盟前身是IBM信息产业事业部,后成立于1991年,自那时起,利盟转型为一家自身品牌、产品、销售、市场体系及产品开发、制造为一体的独立的全球性公司.利盟是目前打印办公行业内少数掌握着打印机核心技术的厂商,除自有丰富的打印产品,还为长城、联想、戴尔、Gateway代工打印机.2011年利盟迎来的20周年生日.