共查询到20条相似文献,搜索用时 93 毫秒
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研究了固溶、时效对挤压添加钙的三种AM50镁合金组织和力学性能的影响。结果表明:合金挤压后,随着固溶时间的增加,Mg17,Al12相以弥散状溶解在基体镁中,而Al2Ca相相当稳定,部分变细,逐步断开并出现球化现象;随着时效时间的增加,Mg177Al12相以粒状从基体中析出,而Al2Ca相在时效过程中变化极小。固溶后,挤压合金的硬度和抗拉强度下降。时效后,挤压添加1%Ca的合金抗拉强度略有升高,未加和加入2%Ca的抗拉强度略有下降,三种合金的硬度增加到峰值后逐步下降。未加和加入29,6Ca的合金固溶后塑性显著增加,时效后塑性略有下降;而加入1%Ca的合金固溶后塑性略有下降,时效后塑性显著提高。 相似文献
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几种6000系汽车板铝合金时效行为及性能的研究 总被引:4,自引:0,他引:4
通过硬度测量、拉伸和成形性试验,并采用透射电镜、扫描电镜及金相分析,研究了ωMg/ωSi和ωMg/ωCu值对几种6000系汽车板铝合金时效行为、力学性能及成形性的影响。结果表明:在时效初期,对于硅过剩合金,其硬度和强度随ωMg/ωSi和ωMg/ωCu值增大而提高;对于镁过剩合金,其比值过大时则硬度和强度显著下降。但伸长率及埃利克森值随比值增大均为降低。此外,增大ωMg/ωCu。值会促进合金时效初期的硬化速度,但ωMg/ωCu过大,初始硬度大为降低,反而不利于合金的时效硬化性。 相似文献
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采用第一性原理计算方法研究了AlCu3合金及Mg、Ag、Si在Al位或Cu位通过取代掺杂方式形成的Al7Cu24X和Al8Cu23X(X=Mg,Ag,Si)合金体系的结构稳定性、电子结构和力学性能。Mg、Ag、Si倾向于在Cu位进行取代掺杂,对AlCu3合金晶体几何结构影响较小,Al7Cu24X和Al8Cu23X(X=Mg,Ag,Si)体系具有很好的热力学稳定性和机械稳定性。态密度和差分电荷密度计算结果表明,Al7Cu24X和Al8Cu23X(X=Mg,Ag,Si)掺杂体系仍然保持明显的AlCu3合金特征,Cu3d价电子轨道对Al7Cu24X和Al8Cu23X(X=Mg,Ag... 相似文献
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镁钙合金的显微组织及力学性能 总被引:4,自引:1,他引:4
应用XRD、SEM、TEM以及短时拉伸试验研究了钙对镁合金组织和性能的影响。结果表明:铸态下,含钙镁合金主要由镁基体和晶界处的离异共晶组织(Mg+Mg2Ca)组成;固溶时效后,晶界处的离异共晶组织消失,代之以颗粒状的Mg2Ca相。铸态合金的常温力学性能较差,但固溶时效后其常温力学性能显著提高,并且在高温短时拉伸时仍然能保持较高的强度。随着含钙量的提高,晶界离异共晶量增加,铸态和时效态的室温抗拉强度和伸长率均下降,时效态高温短时抗拉强度增加,但伸长率仍有所下降。 相似文献
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采用KBF4和K2TiF6混合盐反应工艺原位合成制备了TiB2颗粒增强AlSi7Mg0.6合金(TiB2/AlSi7Mg0.6)复合材料,并进行了固溶和时效处理;用光学显微镜、透射电镜和硬度仪对复合材料的显微组织及热处理强化后的性能进行了研究。结果表明:TiB2颗粒显著细化了复合材料的显微组织;固溶处理后复合材料达到硬度峰值的时效时间较基体合金缩短,峰值硬度提高幅度小于基体合金的;复合材料中铝基体晶粒细小、晶界面积大,导致时效强化相在晶内的析出量不足,是复合材料时效硬度提高幅度下降的主要原因。 相似文献
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采用加压成形工艺制备6063铝合金,然后对铝合金进行535℃固溶和时效处理,研究了固溶时间(15~120 min)、时效温度(160~200℃)和时效时间(1~24 h)对该铝合金显微组织、拉伸性能和硬度的影响.结果表明:随着固溶时间的延长,6063铝合金晶粒尺寸增大,Mg2Si初生相逐渐消失并回溶至基体中,而固溶时间未对α-Al8Fe2Si相和β-Al5FeSi相的含量与形貌产生影响;固溶处理后,随着时效温度的升高或时效时间的延长,第二相Mg2Si数量增加,但过高的时效温度或过长的时效时间导致Mg2Si相粗大;随着固溶时间、时效时间的延长,或时效温度的升高,合金的强度和硬度先升高后降低,断后伸长率先减小后增大;6063铝合金适宜的固溶和时效处理制度为535℃×60 min+180℃×7 h,此时合金中析出的Mg2Si相最细小,且弥散分布,合金具有最高的强度和硬度,以及合适的断后伸长率. 相似文献
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In a recent paper, the Ritz method with simple algebraic polynomials as trial functions was used to obtain an eigenvalue equation for the free vibration of a class of homogeneous solids with cavities. The method presented is here extended to the study of a class of non-homogeneous solids, in which each solid is composed of a number of isotropic layers with different material properties. The Cartesian coordinate system is used to describe the geometry of the solid which is modelled by means of a segment bounded by the yz, zx and xy orthogonal coordinate planes and by two curved surfaces which are defined by fairly general polynomial expressions in the coordinates x, y and z. The surface representing the interface between two material layers in the solid is also described by a polynomial expression in the coordinates x, y and z. In order to demonstrate the accuracy of the approach, natural frequencies are given for both a two- and three-layered spherical shell and for a homogeneous hollow cylinder, as computed using the present approach, and are compared with those obtained using an exact solution. Results are then given for a number of two- and three-layered cylinders and, to demonstrate the versatility of the approach, natural frequencies are given for a five-layered cantilevered beam with a central circular hole as well as for a number of composite solids of more general shape. 相似文献
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通过分析膨胀套在实际使用产生滑移受阻现象、卡死现象原因的实质,并在分析产生问题原因的基础上提出了改进措施即:增加导向机构。 相似文献
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Polyvinyl pyrrolidone-Iodine complex (PVP-I) molecules were impregnated into the anodic oxide of an aluminum disk specimen. It was rubbed against a silicon nitride ball specimen using a ball-on-disk type friction test rig. Over the limited range of parameters studied (load: 0.2-1.0 N, sliding velocity: 0.6 mm/s, and sliding distance: 1-7 m), the coefficient of friction decreased to a value as low as 0.01 from values of 0.3 to 0.7 for the anodic oxide surface. Single-crystal iodine rubbed against silicon nitride showed a coefficient of friction of 0.1. The low coefficient of friction is attributed to the thin PVP-I film on the relatively hard anodic oxide. The mechanism of coefficient of friction reduction is the same as that of a thin soft film on a hard substrate. 相似文献
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针对目前市场对工业设计人才的需求,本文论述了我校在工业设计教育方面的改革措施,着重介绍了我校工业设计教育在软件和硬件方面所进行的一系列的改革。 相似文献
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设计了磨粉机快辊轴承座的加工工艺和具体的工装夹具.利用卧式加工中心加工磨粉机快辊轴承座,辅以能够高效快速夹紧的夹具,既可以保证加工精度,又能够提高加工效率. 相似文献
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本文以某些积算和双笔记录仪产品为例说明由于仪表功能设计的不合理或选型不当,影响了仪表的正常使用,制造厂和用户应关注这类问题。 相似文献
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The article provides a solution to the problem of contraction process modeling when measuring the flow of fluids and gases using differential pressure flowmeters. The article shows the feasibility of obtaining the coefficient of contraction from the mathematical model of the reduced/contracted flow of fluids or gases. An analytical expression is obtained for the coefficient of contraction, which agrees well with the results of the experiment. Analysis of this expression is performed and dependencies on the geometrical parameters of the pipeline and orifice plate are obtained. 相似文献