铬青铜和铜铬锆热处理前后的显微组织

采用高分辨的透射电子显微镜分析铬青铜和铜铬锆在固溶时效处理前后的显微组织。结果表明,铬青铜和铜铬锆合金在固溶时溶解于铜基体的强化相Cr在时效后弥散均匀分布在基体Cu上。铬与铜没有中间相或化合物形成,铜铬锆固溶时效处理后组织中的析出相要比铬青铜组织中的析出相尺寸小,铜铬锆晶界处偏聚的析出相尺寸也比铬青铜晶界处的析出相小,而且添加锆所构成的铜合金则有Cu5Zr相的析出。     

铬青铜高温力学性能研究

研究了铬青铜的室温至900℃的拉伸性能和微观组织,以及合金在应变速率为0．01s^-1时的高温应力-应变关系。结果表明,该材料在900℃时屈强比较低,合金的伸长率与断面收缩率较高．塑性最好。材料的强度随温度的升高而下降。高温应力应变曲线可分为3个阶段：微应变区,过渡变形区和稳态变形区。铬青铜的高温断裂特征表现为局部韧性断裂。     

触头材料—铬青铜内氧化的研究

本研究表明，低铬青铜在空气中于１０００℃下固溶处理后，将出现外氧化和铬的内氧化，外氧化使合金表面贫铬，内氧化将降低合金固溶时效强化效果，文中讨论了铬青铜的内氧化热力学条件，特殊的内氧化机理，外氧化对内氧化的影响等。     

热处理对铬青铜组织和性能的影响

研究了均匀化处理、固溶时效、冷变形时效等对铬青铜显微组织和性能的影响。结果表明:均匀化处理可有效改善铬在铜基体中的分布;铬青铜的最佳固溶工艺为:1000℃保温1h后水淬;较好的时效工艺为470℃×4h,此时合金的硬度和电导率分别为121.5HV和79.8%IACS。时效前经适当的冷变形,其硬度为146.7HV,电导率为85%IACS,和未冷变形直接时效相比分别提高了25.2HV和5.2%IACS。     

热处理对铬青铜组织和性能的影响

研究了均匀化处理、固溶时效、冷变形时效等对铬青铜显微组织和性能的影响.结果表明均匀化处理可有效改善铬在铜基体中的分布;铬青铜的最佳固溶工艺为1000℃保温1 h后水淬;较好的时效工艺为470℃×4 h,此时合金的硬度和电导率分别为121.5 HV和79.8%IACS.时效前经适当的冷变形,其硬度为146.7 HV,电导率为85%IACS,和未冷变形直接时效相比分别提高了25.2 HV和5.2%IACS.     

铝青铜合金热变形流变应力特征

采用Gleeble-3500热模拟机进行圆柱体压缩试验,研究了新型铝青铜合金在变形温度为650～950℃、应变速率为0.01～5s-1、真应变为0～0.8条件下的流变应力特征。结果表明:应变速率为0.01和5s-1时,铝青铜合金首先出现加工硬化,流变应力达到峰值后趋于平稳,表现出动态回复的特征;应变速率为0.1和1s-1时,合金发生了局部动态再结晶;可用Zener-Hollomon参数的双曲正弦形式来描述新型铝青铜合金热压缩变形时的流变应力行为。     

QCr0.5铬青铜熔炼的生产实践

铬青铜合金具有较高的强度和硬度,以及优良的导电导热性能、耐磨和耐热性能,并易于压力加工,可用于制造电机整流子和电焊机的电极,以及在高温下要求具有高强度、硬度、高导电性和导热性的零件等,还可制成双金属用于刹车盘和圆盘等.     

热处理对锡青铜合金组织和性能的影响

以ZQSn10-2锡青铜合金成分为基础,研究加入少量的Ni和后续扩散退火热处理对合金组织结构和性能的影响.研究结果表明:合金组织为α-Cu固溶体和〥相,〥相沿晶界析出,含有较高的Sn和Ni,通过500～600℃热处理.部分〥相扩散固溶到α-Cu相中,使得合金强度和伸长率大幅度提高.     

93W与98W粉末冶金材料摩擦焊接头性能及组织分析

为了充分利用93W钨合金和98W钨合金两种粉末冶金材料各自独特性能优势,开发基于这两种钨合金的复合材质是非常必要的.采用自主研制的HSMZ-10型摩擦焊机,利用优选的焊接工艺参数,将93W钨合金和98W钨合金在主轴转速为2 000r/min,摩擦变形量为5 mm,摩擦压力为30 MPa,顶锻压力为60 MPa,摩擦顶锻变形速率为20 mm/s的条件下,通过摩擦焊接方法成功地实现了焊接,并对接头和母材进行了金相组织分析和力学性能检测分析.结果表明,接头力学性能良好,无未焊透等焊接缺陷;93W和98W粉末冶金材料之间无成分均一化现象,焊缝的强度大于母材.     

形变热处理对铸造锡青铜组织与力学性能的影响

采用真空离心铸造方法制备了ZCu Sn10Zn2Fe Co锡青铜合金试样,通过对合金进行固溶处理、压缩变形以及随后的时效处理,研究形变及时效过程对合金显微组织及力学性能的影响规律。结果表明,形变热处理能够通过再结晶显著细化合金晶粒,晶粒大小由固溶态的20~40μm降低到几个微米,小部分晶粒发生了二次再结晶长大,XRD分析表明形变热处理后合金中并未产生新相;时效前的预冷变形能显著提高合金的力学性能,40%形变热处理后合金的布氏硬度由固溶态的92 HBW提高到146 HBW。     

Superplastic solid state welding steel and copper alloy based on laser quenching of steel surface

Based on the feasibility of isothermal superplastic solid state welding of steel and copper alloy, the welded surface of steel surface was ultra-fined through laser quenching, and then the welding process tests between different base metals of 40Cr and QCr0.5 were made under the condition of non vacuum and non shield gas. The experimental results show that, with the sample surface of steel after laser quenching and that of copper alloy carefully cleaned, and under the pre-pressed stress of 56.6 -84.9 MPa, at the welding temperature of 750 -800 ℃ and at initial strain rate of (2.5 - 7.5) × 10-4 s-1 , the solid state welding can be finished in 120 - 180 s so that the strength of the joint is up to that of QCr0.5 base metal and the expansion rate of the joint does not exceed 6%. The plastic deformation of the joint was further analysed. The superplastic deformation of the copper alloy occurs in welding process and the deformation of steel are little.     

置氢TC4钛合金激光焊接接头超塑变形组织均匀性分析

文中采用置氢处理的方式对钛合金激光焊接接头超塑性变形组织均匀性展开研究,研究不同的置氢量对TC4钛合金激光焊接头变形均匀性和组织均匀性的影响,并引进变形不均匀性系数和组织均匀化系数来进行表征. 结果表明,置氢可以调节钛合金激光焊接接头中相组成,改善焊接接头超塑性变形均匀性. 随着置氢量的增大,组织均匀化系数越大,组织均匀化程度越高;在相同置氢量,变形温度的升高或初始应变速率的降低均会使均匀化程度上升,并在置氢量1.30%、变形温度920 ℃、应变速率1×10-4s-1的条件下接头组织均匀化系数达到了95%.     

双相NiAl金属间化合物超塑性

研究双相Ni-31Al金属间化合物的高温变形行为。结果表明,该合金在950~1075℃温度范围,1.25×10-4~8×10-3s-1应变速率范围内呈超塑性变形。在温度为1000℃、应变速率为5×10-4s-1时,最大延伸率可达281.3%。显微结构分析表明,超塑性变形过程中两相具有很好的协调变形能力,超塑性变形后原始组织拉长、细化。双相Ni-31Al金属间化合物超塑性变形机制可能为连续动态回复与再结晶。     

Isothermal superplastic solid state bonding of 40Cr and Cr12MoV steels based on surface modification

Based on the feasibility of isothermal superplastic solid state bonding of 40Cr and Cr12MoV steels, the surfaces of both steels to be bonded were ultra-fined through high frequency hardening, then the superplastic solid state bonding were conducted, the microstructure and fracture surface of bonded joint were observed and analysed, and bonding mechanisms was researched. The experimental results show that with the sample surfaces of 40Cr and Cr12MoV steels after the high frequency hardening, under the prepressing stress of 56.6 MPa, initial strain rate of 1.5×10~(-2) min~(-1) and at the bonding temperature of 800-820℃, the superplastic solid state bonding can be carried out in about 3.5min, and the joint strength is up to that of 40Cr steel base metal and the radial expansion ratio of the joint does not exceed 6%. The superplastic solid state bonding parameter of both steels is within the ranges of the isothermal compressive superplastic deformation of Cr12MoV steel, and the deformation in Cr12MoV steel side near the interfacial zone of joint presents the characteristic of superplasticity. In bonding process, the atoms in two sides of joint interface have diffused each other.     

Microstructural evolution and grain boundary sliding in a superplastic magnesium AZ31 alloy

Tensile experiments on a fine-grained single-phase Mg–Zn–Al alloy (AZ31) at 673 K revealed superplastic behavior with an elongation to failure of 475% at 1 × 10^?4 s^?1 and non-superplastic behavior with an elongation to failure of 160% at 1 × 10^?2 s^?1; the corresponding strain rate sensitivities under these conditions were ～0.5 and ～0.2, respectively. Measurements indicated that the grain boundary sliding (GBS) contribution to strain ξ was ～30% under non-superplastic conditions; there was also a significant sharpening in texture during such deformation. Under superplastic conditions, ξ was ～50% at both low and high elongations of ～20% and 120%; the initial texture became more random under such conditions. In non-superplastic conditions, deformation occurred under steady-state conditions without grain growth before significant flow localization whereas, under superplastic conditions, there was grain growth during the early stages of deformation, leading to strain hardening. The grains retained equiaxed shapes under all experimental conditions. Superplastic deformation is attributed to GBS, while non-superplastic deformation is attributed to intragranular dislocation creep with some contribution from GBS. The retention of equiaxed grain shapes during dislocation creep is consistent with a model based on local recovery related to the disturbance of triple junctions.     

Ti40阻燃合金粗晶超塑性变形行为及机理

借助OM、TEM研究了高温条件下Ti40阻燃合金的粗晶超塑性变形行为及机理。结果表明:在920℃下,应变速率为5×10-5～1×10-2s-1的Ti40合金表现出良好的超塑性行为,拉伸延伸率均超过250%,应变速率敏感指数m大于0.3。超塑变形后,粗大的等轴组织细化。TEM分析表明,在变形过程中,位错运动形成亚晶界,亚晶界通过吸收滑移位错形成小角度晶界甚至大角度晶界。Ti40合金的粗晶超塑性是由动态回复和再结晶共同作用的结果。     

Er、Zr微合金化5083铝合金的超塑性

针对5E83合金(Er、Zr微合金化5083合金),采用超塑性拉伸试验、扫描电镜(SEM)、电子背散射衍射(EBSD)和透射电镜(TEM),探究了Er、Zr微合金元素、晶粒尺寸、变形温度、应变速率对合金超塑性的影响。通过再结晶退火、空冷和水冷的搅拌摩擦加工(FSP),分别获得了晶粒尺寸为7.4、5.2、3.4μm的完全再结晶组织,作为初始状态进行超塑性拉伸。结果表明,初始晶粒尺寸越细小,超塑性伸长率越高。当晶粒尺寸>5μm时,超塑性变形过程晶粒粗化缓慢,细化初始晶粒可显著提高超塑性;而当晶粒尺寸<5μm时,超塑性变形过程晶粒粗化严重,进一步细化初始晶粒对超塑性的提高有限。不同变形温度、应变速率的超塑性拉伸结果显示在变形温度为450～540℃、应变速率为1.67×10^-4～1.67×10^-1 s^-1,超塑性伸长率随变形温度和应变速率的提高呈现先上升后下降再上升的趋势;变形温度为520℃、应变速率为1.67×10^-3 s^-1条件下,水冷FSP态合金获得最大伸长率330%...     

Effect of current pulses on fracture morphology in superplastic deformation of 2091 Al Li alloy

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QBe2铍青铜与Cr20Ni80镍铬丝的微型件电容储能点焊

阐述了在微型电机电刷零部件的生产过程中,铍青铜与镍铬丝电容储能点焊的工艺过程,分析了微型件点焊的特殊性,计算了微型件的热时间常数τ,且根据选择的规范参数及焊接电流波形,提出了τ及电流上升时间之间的一些对应关系,并对焊接接头的金相组织,元素扩散以及力学性能进行了分析试验.发现采用电容储能点焊机对QBe2铍青铜与Cr20Ni80镍铬丝微型件进行焊接可以获得良好的焊接接头,焊接界面铍青铜一侧有晶界局部熔化现象,焊点的抗拉强度为375MPa,镍铬合金中的镍元素与铬元素有向铍青铜中扩散的现象.     

氢对Ti-6Al-4V合金组织及超塑变形行为的影响

应用光学显微镜研究氢对Ti-6Al-4V显微组织的影响,并在温度800℃～860℃和应变速率10-3s-1的变形条件下进行超塑拉伸实验。结果表明,随着氢含量的增加,β相的比例提高,且由等轴组织转变为双态组织,随着氢含量的进一步增加,在α相中形成了氢化物;同时,适量的氢可以显著降低Ti-6Al-4V合金峰值应力,置氢0.32wt%H,其峰值流动应力降低了约55%;此外,适量置氢可以显著降低Ti-6Al-4V合金的超塑性变形温度,较原始合金最佳超塑变形温度可降低60℃～100℃,置氢0.11wt%H,在840℃获得了1190%的延伸率,较相同条件下的原始合金延伸率提高75%。文章研究结果可为超塑成形、超塑成形/扩散连接工艺及生产提供优化参考。