Y.W.Bao
,
Y.C.Zhou
金属学报(英文版)
Creep and stress relaxation behavior, the elastic modulus and fracture toughness of machinable Ti3SiC2 at various temperatures from 20 to 1250℃ were investigated by means of three-point bending tests. The experiments were performed respectively at: (i) fixed stress and changed temperatures, and (ii) fixed temperature and changed stresses. A creep resistance parameter that represents the probability of creep deformation in a given condition was defined as a function of both applied stress and the threshold stress, varying in a range from 0 to 1. Elastic modulus at high temperatures was measured through comparing relative slopes of loading curves in cyclic loading curve. The fracture toughness measured by SENB method showed a stable value in the range of 25-1000℃, but over 1000℃, it declined abruptly from ～6.7MPa.m^1/2 to～2.0MPa.m^1/2 at 1200℃.
关键词:
high-temperature
,
null
,
null
Y.W.Bao
,
Y.F.Han
,
F.T.Gong
金属学报(英文版)
Stress relaxation of glass is a dualism effect, it often lead to strength degradation in strengthened glass, but on the other hand, it improves the reliability and stressuniformity of glasses. In this work, stress relaxation of soda-lime glass was investigated using three-point bending tests at 400-560℃ which is near the brittle to ductile transition temperature, for enhancing the safety of glass productions and exploring the most economic anneal process. The experimental results show that the speed of stress relaxation increases but the ultimate stress decreases with increasing temperature. The stress uniformity of the glass samples before and after anneal was examined using spherical indentation at arranged testing points. It indicates that the scatter of the local strength measured by the Hertzian indentation is smaller in the anneal glass than in initial specimen, so that the estimated Weibull modulus for the anneal specimen is higher. Furthermore, the strength evaluation by Hertzian indentation and statistical analysis was presented.
关键词:
glass
,
null
,
null
彭石高
,
丁飞
,
中国有色金属学报
采用溶胶-喷雾干燥-氢还原法制备稀土Y含量分别为0,0.4%,5%,10%和20%的超细(W,Ni,Fe,Y)复合粉末,采用XRD研究煅烧温度和还原温度以及稀土Y含量变化时复合粉末体在制备过程中的相结构变化规律.结果表明:喷雾干燥前驱体随煅烧温度的升高渐渐从非晶体向复合氧化物晶化转变,添加稀土Y的粉末前驱体经煅烧后,Y与W形成复合氧化物Y2W3O12,且稀土Y可以有效地抑制粉末颗粒长大;随着Y含量的增加,Y和W的复合氧化物明显增加,Y2W3O12在700℃才能被还原成低氧复合氧化物相:含5%稀土Y粉末中的Y2W3O12被还原生成新相Y2WO6;当稀土Y增加到10%以上时,不仅生成Y2WO6,还生成另一种新相Y6W2OB15.
关键词:
W-Ni-Fe复合粉末
,
纳米粉末
,
稀土
,
Y
姜迪友
,
刘三秋
稀有金属材料与工程
采用基于密度泛函理论的第一性原理方法研究了钇的含量对W-Y二元合金力学性质的影响,精确计算了W1-xYx(x=0.0625,0.125,0.25,0.5)合金的力学常数,并对其力学特性进行分析.结果表明,W-Y合金的弹性常数、体模量、杨氏模量以及剪切模量随Y含量(原子分数)的增加而成非单调性减小,表明Y对W材料的合金化降低了材料的机械强度.然而,基于力学特性B/G、泊松比v和柯西压力C等分析,Y的合金化对W的延展性和韧性有明显的提高.当Y含量x为0.25时,可有效改善W-Y合金的延展性和抗变形能力.通过态密度分析,W-Y合金的金属性随Y含量的增加先减弱而后增强.
关键词:
第一壁材料
,
W-Y合金
,
力学性质
,
第一性原理
,
密度泛函理论
高原
,
张维
,
王成磊
,
李冰
,
陈选楠
,
黄学锋
,
袁琳
材料热处理学报
研究Q235钢表面等离子W-Mo-Y共渗层的组织、成分、结构、显微硬度,计算渗层中不同位置、浓度下的W、Mo原子扩散系数。结果表明：渗层组织为柱状晶,W、Mo元素呈梯度分布,Y的分布不均匀。共渗层主要结构相为钨钼在α-Fe中的固溶体和Fe17Y2,共渗层显微硬度最高256 HV0.05;Y元素降低表面W、Mo的活度,W、Mo合金元素的化学势变小,表面与基体之间的化学梯度减小,W、Mo原子扩散速率减慢;W-Mo-Y共渗层厚度要比W-Mo共渗层厚度薄;通过Fick第二扩散定律计算表明,在W-Mo-Y共渗和W-Mo共渗时,不同渗层中的W、Mo扩散系数有所不同,但属同一数量级即：10-13～10-14之间。
关键词:
等离子渗金属
,
晶界
,
活度
,
化学梯度
,
化学势
,
Fick第二扩散定律
Journal of Alloys and Compounds
This work mainly investigated the mechanical properties of as-cast Mg-Zn-Y-Zr Mg alloys with Zn/Y ratio about 0.97. Tensile results show that when Zn/Y ratio is constant, the alloy (with Zn and Y contents of 3.93 and 4.14 wt.%, respectively) has the highest strength. XRD analysis shows that the alloys are mainly composed of alpha-Mg matrix and W-phase. With the contents of Zn and Y increasing, the diffraction peaks of W-phase are gradually intensified. In addition, microstructure observation indicates that with the increase of Zn and Y contents, the grain boundaries are gradually coarsened by W-phase. Based on the microstructure observation and fracture analysis, the change of the mechanical properties has been explained. (C) 2007 Elsevier B.V. All rights reserved.
关键词:
Mg-Zn-Y-Zr alloys;the mechanical properties;W-phase;icosahedral phase;microstructure;behavior
李冰
,
高原
,
陈选楠
,
黄学锋
,
赖涛
,
陈文琦
表面技术
doi:10.3969/j.issn.1001-3660.2011.01.025
采用辉光等离子渗金属技术对Q235钢进行W-Mo-Y三元共渗,探讨了极间距、气压、保温时间、温度对共渗层厚度的影响,并分析了共渗层的金相显微组织、合金元素分布及物相组成.结果表明:在试验涉及的条件下,以极间距25 mm,气压30 Pa,保温时间3 h,温度1000℃为最佳工艺参数;共渗层主要由Fe3Mo,Fe(Mo,W,Y),Fe17Y2等组成,组织为柱状晶,W和Mo的含量由表及里逐渐减少,而Y元素由于在晶界处发生偏聚而分布不均匀.
关键词:
等离子渗金属
,
W-Mo-Y共渗
,
Q235钢
马运柱
,
黄伯云
,
范景莲
,
熊翔
,
魏定池
,
汪登龙
中国稀土学报
以喷雾干燥法制备的(W,Ni,Fe)复合氧化物粉末为原料,采用700 ℃,保温90 min的条件进行还原,研究了La-Y含量对还原制备纳米级W-Ni-Fe复合粉末特性的影响;采用XRD及高倍SEM分别对所制备的复合粉末进行了物相分析、晶粒尺寸测试和形貌观察;并对所制得复合粉末的Fsss粒度、比表面进行了测定与分析.研究结果表明: 不加La-Y时还原粉末由W和γ-(Ni,Fe)两相组成,添加一定量La-Y的还原粉末有W,γ-(Ni,Fe),Y(Ni0.75W0.25)O3和La (Ni0.75W0.25)O3四相组成;当La-Y的质量分数在0～0.8%范围时(占90W-7Ni-3Fe复合粉末的质量分数),随着La-Y含量的增加,粉末dBET粒度由96.6降到50.3 nm,粉末Fsss粒度由0.64降到0.33 μm,粉末晶粒尺寸由26.1降到22.2 nm;未添加La-Y时粉末颗粒为球形,添加一定量的La-Y,粉末颗粒变为近球形或多面体;添加一定量的La-Y不仅可以有效地抑制晶粒长大,还可以在一定程度上提高粉末的分散性.
关键词:
材料学
,
W-Ni-Fe复合粉末
,
纳米级粉末
,
氢还原
,
稀土
杨广宇
,
刘咏
,
王岩
,
李建波
,
唐蓓
,
李慧中
中国有色金属学报
采用光学显微镜、扫描电镜及透射电镜研究微量B和Y对铸造Ti-AIl-Nb-W合金显微组织的影响.结果表明:Ti-47Al-4Nb-0.6W合金的基本凝固路线为L→β+L→(β+a)+L→(β+a)+γ→aa+γ→(a-γL)+γ→(a2+γ<,L>)+γ,添加微量B和Y并未改变其基本凝固路径;微量B元素在合金中以短棒状TiB2相存在,细化了铸造Ti-47Al-4Nb-0.6W合金的晶团尺寸及片层间距;微量稀土Y元素主要以Y2O3氧化物颗粒的形式分布于片层晶团界面处,在B和Y的共同作用下,合金的片层晶团尺寸以及片层间距进一步减小.
关键词:
TiAl基合金
,
显微组织
,
铸造合金
,
B
,
Y
马运柱
,
黄伯云
,
刘文胜
,
汪登龙
稀有金属材料与工程
采用SEM和金相仪器对添加不同Y量的纳米粉90W-7Ni-3Fe合金试样断口进行形貌观察和W晶粒测试;并对烧结态试样的相对密度、抗拉强度、延伸率等性能进行测定与分析.结果表明:当Y量在0.2%～0.6%(质量百分数,下同)时,试样相对密度为99.2%～99.6%,抗拉强度为1000 MPa～1100 MPa,延伸率为16%～19.5%;添加0.4%Y后,W晶粒从原来的20 gm～25μm减小到12μm,W晶粒形状由不加稀土时的球形变为近球形或多边形.添加0.4%Y后,在界面上形成了W13.07Ni2.96Fe1.52Y23.65Ox(摩尔数比)的中间相,其阻止了W原子在粘结相中的扩散,阻止了W晶粒长大,细化了W晶粒,提高了合金的性能.
关键词:
90W-7Ni-3Fe合金
,
纳米级粉末
,
稀土Y
,
烧结特性
