Journal of Materials Research
The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.
关键词:
room-temperature
荀玉强
,
杨鲁伟
,
蔡京辉
,
梁惊涛
,
周远
工程热物理学报
介绍了一套实用型单级高频同轴脉冲制冷机工作在深低温区的性能特性.输入功率为200 W时,冷头无负荷最低温度可达到29.35 K,输入功率为235 W时,冷头无负荷温度可稳定在28.55 K.这是目前国内无多路旁通的单级高频脉冲管制冷机获得的最低温度,国际上位于先进行列.200 W输入条件下,35.6 K可提供0.5 W制冷量,为30～40K温区相关的小冷量应用提供了一种简单有效的方法.
关键词:
脉冲管制冷机
,
高频
,
单级
,
同轴
,
双向
徐宏扬
,
柯海波
,
黄火根
,
张培
,
张鹏国
,
刘天伟
金属学报
doi:10.11900/0412.1961.2016.00322
在室温下利用纳米压痕测试技术研究了峰值载荷和加载速率对U65Fe30Al5新型非晶合金蠕变行为的影响规律。结果表明,随着峰值载荷和加载速率的增加,在相同蠕变时间内,蠕变位移呈增大趋势,但当加载速率高于特定阈值时,蠕变位移不再增大。通过蠕变经验公式拟合发现,蠕变过程的应力指数随峰值载荷的增加不断变大,但随加载速率的增加先减小后基本恒定。与常规晶态合金相比,U65Fe30Al5非晶合金具有更大的应力指数,这反映出后者内部结构中富含自由体积。
关键词:
非晶合金
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铀合金
,
纳米压痕
,
蠕变行为
,
应力指数
赵秀明
,
章晓波
,
方信贤
,
王章忠
,
薛亚军
材料热处理学报
研究了不同挤压速度挤压出的Mg-3.0Nd-0.2Zn-0.4Zr(质量分数,％,NZ30K)镁合金显微组织和室温力学性能.采用光学显微镜观察了合金的显微组织,采用材料拉伸试验测试了合金的室温力学性能,并利用扫描电子显微镜观察了拉伸试样的断口形貌和断口附近的显微组织.结果表明:当挤压速度相对较低时,发生部分再结晶,组织不均匀,合金的强度很高,而塑性则较差;当挤压速度较高时,合金发生了完全动态再结晶,组织均匀,再结晶晶粒明显长大,合金强度降低,而伸长率则明显提高.合理控制挤压速度可获得细小均匀的组织和良好的综合力学性能.
关键词:
镁合金
,
显微组织
,
力学性能
,
挤压速度
王小娜
,
韩利战
,
顾剑锋
金属学报
doi:10.3724/SP.J.1037.2013.00478
利用等转变量方法和恒速升温时效过程中的电阻实验研究了NZ30K镁合金的析出动力学,获得了动力学模型的激活能Eαr和修正指前因子Aαr,可用于准确描述不同时效条件下强化相的析出过程.NZ30K镁合金欠时效阶段和峰时效的力学性能显示,在180～250℃范围内峰时效屈服强度一致,约为150MPa.通过最小二乘法确定了NZ30K镁合金180～250℃范围内时效时析出强化模型参数C,约为93MPa,实验数据和模型预测数据一致,证明该模型能应用于NZ30K镁合金欠时效和峰时效条件下屈服强度的预测.
关键词:
NZ30K镁合金
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析出动力学
,
沉淀强化
,
固溶强化
,
屈服强度
Communications in Theoretical Physics
By means of both a theory for pressure-induced shifts (PS) of energy spectra and a theory for shifts of energy spectra due to electron-phonon interaction (EPI), the 'pure electronic' PS and the PS due to EPI of R-1 line, R-2 line, and U band of GSGG:Cr3+ at 300 K have been calculated, respectively. The calculated results are in good agreement with all the experimental data. Their physical origins have also been explained. It is found that the mixing-of degree \t(2)(2)(T-3(1))e(4)T(2)> and \t(2)(3) 2E> base-wavefunctions in the wavefunctions of R-1 level of GSGG:Cr3+ at 300 K is remarkable under normal pressure, and the mixing-degree rapidly decreases with increasing pressure. The change of the mixing-degree with pressure plays a key role not only for the 'pure electronic' PS of R-1 line and R-2 line but also the PS of R-1 line and R-2 line due to EPI. The pressure-dependent behaviors of the 'pure electronic' PS of R-1 line (or R-2 line) and the PS Of R-1 line (or R-2 line) due to EPI are quite different. It is the combined effect of them that gives rise to the total PS of R-1 line (or R-2 line). In the range of about 15 kbar similar to 45 kbar, the mergence and/or order-reversal between t(2)(2)(T-3(1))e(4)T(2) levels and t(2)(32)T(1) levels take place, which cause the fluctuation of the rate of PS for t(2)(2)(T-3(1))e(4)T(2) (or t(2)(3) T-2(1)) with pressure. At 300 K, both the temperature-dependent contribution to R-1 line (or R-2 line or U band) from EPI and the temperature-independent one are important.
关键词:
high-pressure effect;spin-orbit interaction;electron-phonon;interaction;d orbital;coupling between t(2)(2)(3T(1))e(4)T(2) and;t(2)(32)E;tunable laser crystal;theoretical calculations;temperature-dependence;thermal broadenings;garnet crystals;cr3+ ions;r-line;cr-3+;luminescence;ruby;spectroscopy
章晓波
,
薛亚军
,
王章忠
,
袁广银
,
马欣宇
材料热处理学报
通过对具有高屈强比的生物镁合金Mg-2.98Nd-0.34Zn-0.46Zr(NZ30K)进行退火与时效处理,研究了退火与时效处理后合金的显微组织、室温力学和腐蚀性能.结果表明,退火与时效处理后粗大的被拉长的晶粒被消除,随退火温度提高,晶粒逐渐粗大,屈服强度降低,而抗拉强度仍保持较高值.试验研究的5种状态合金的屈强比分别为0.98、0.82、0.71、0.60和0.55；在模拟体液中,与挤压时效态合金的腐蚀性能相比,随退火温度升高,退火与时效处理后合金的腐蚀速率先减慢后加快,且为均匀腐蚀.适宜的热处理工艺有效降低合金屈强比,同时稍微提高合金的耐蚀性能.
关键词:
生物镁合金
,
显微组织
,
屈强比
,
腐蚀性能
