冷轧及热处理对AA 5052铝合金组织及力学性能的影响

通过光学显微镜、扫描电镜、X射线衍射分析、硬度实验和拉伸实验等方法,研究不同轧制变形量及后续退火处理对均匀化态5052铝合金组织与性能的影响。研究结果表明,随着轧制变形量的增加,等轴晶沿着轧制方向明显地被拉长。由于轧制变形量的增加,加工硬化效应导致合金强度升高,硬度下降。当轧制变形量为87%时,抗拉强度可达325 MPa,但是伸长率只有2.5%。经退后处理后,大量的第二相析出。随着退火温度的升高,第二相析出增多,并且明显弱化加工硬化效应。当经过300°C处理4 h后,伸长率可达~23%,抗拉强度降至212 MPa,此时综合力学性能恢复到均匀化状态。     

Influence of impurities on microstructure and mechanical properties of ZK60 magnesium alloy

The influence of impurity content on the microstructure and mechanical properties of ZK60 magnesium alloys was investigated by optical microscopy, scanning electron microscopy and tensile test. ZK60 alloys were prepared by changing holding time of alloy melt during semi-continuous casting in order to control the content of impurity elements. The alloy with lower purity content is found to have less second precipitates and larger grain size in the as-cast state. However, in the as-extruded state, reducing impurities brings about a decrease in grain size and an increase in yield strength from 244 MPa to 268 MPa, while the elongations in the as-extruded alloys with different contents of impurities are almost the same. After T5 treatment, impurity content is found to have more obvious effect on the yield strength of ZK60 alloy. The yield strength of ZK60-45 alloys with low impurity content is increased up to 295 MPa after T5 treatment.     

Influence of impurities on damping properties of ZK60 magnesium alloy

The influence of impurities on damping capacities of ZK60 magnesium alloys in the as-cast, as-extruded and T4-treated states was investigated by dynamically mechanical analyzer at room temperature. Granato and Lucke dislocation pinning model was employed to explain damping properties of the alloys. It is found that reducing impurity content can decrease the amount of second-phase particles, increase grain size and improve damping capacity of the as-cast alloy slightly. The as-extruded alloy with lower impurity content is found to possess obviously higher damping capacity in the relatively high strain region than that with higher impurity concentration, which appears to originate mainly from different dislocation characteristics. The variation tendency of damping property with change of impurity content after solution-treatment is also similar to that in the as-extruded and as-cast states. Meanwhile, the purification of the alloy results in an evident improvement in tensile yield strength in the as-extruded state.     

大学知识工作者个体工作胜任力研究

本文在个体能力五个维度方面采用探测性调研法确定大学知识工作者个体工作胜任能力元素，并对各能力元素对科研类工作和教学类工作的重要性进行描述性比较统计，用以判断这些要素在工作中的作用和不同性质工作之间的差异。     

00Cr22Ni5Mo3N双相不锈钢的低温超塑性研究

通过恒温热拉伸的方法研究了太钢生产的00Cr22Ni5Mo3N双相不锈钢的超塑性行为,其中重点研究了该材料的低温超塑性。在850℃的超塑性变形过程中,当初始应变速率为2.5×10~(-3)s~(-1)时,获得了500％的最大延伸率。在800℃～900℃的低温区,δ铁素体分解成γ和σ相,从而导致最终的δ/γ和γ/σ组织。微观组织分析表明:该双相不锈钢超塑性变形的机理是形变诱导相变、晶界的滑移和晶粒的转动。     

欧美地区中文古籍数字化概述

对欧美地区中文古籍书目数据库和古籍全文数据库建设情况作了较为全面的调查和分析。     

二乙二醇二丁醚的合成

二乙二醇二丁醚 (C_4H_9—O—C_2H_4—O—C_2H_4—O—C_4H_9)俗称二丁基卡必醇(Dibutyl Carbitol),是一种重要的工业溶剂。主要用于香料和制药工业。作为工业萃取剂,曾用于铀的提取和钋的分离,七十年代又用于黄金的提取,我国也已应用于贵金属的萃取分离。二乙二醉二丁醚的大规模生产是以环氧乙烷和正丁醇为原料制备的。但由于环氧乙烷的沸点低(10.4℃),易燃易爆,小批量生产不便采用。批量生产和实验室合成仍常以氯乙醇     

旧水泥混凝土路面加铺沥青混凝土面层施工方法的探讨

在对旧水泥混凝土路面加铺沥青混凝土面层出现反射裂缝的原因进行分析的基础上,从中间夹层及加铺面层材料的选择和施工技术等方面,给出了减少反射裂缝的解决方案,有效地改善道路的使用品质,延长道路的使用寿命,获得了十分可观的经济效益。     

振动时效工艺简介及应用

介绍振动时效工艺主要是选择适当的激振力及激振频率使工件产生共振，从而消除或均衡工件的内在应用力。     

中国企业家的崛起：突破传统文化与体制

始于1978年党的十一届三中全会所发起的改革开放,既是对我国传统的计划经济体制的突破,也是对我国传统文化的突破,正是在这两种突破的潮流中,企业家群体便应运而生。第一部分企业家产生于那些在改革开放初期就没有工作的“海中人”。1978年中国共产党十一届三中全会所倡导的改革是中国20世纪80年代以来社会变革的历史契机。在所有制方面突破了公有制一统天下的局面,提倡、鼓励一些非公有制经济的发展,同时对它们留下了计划分的市场缺口,在流通领域里的也网开一面,为私营经济留下了发展的空间。另一方面促使公有经济向现代企业模式进…