材料期刊网

MAfHEMAfICAL MODEL FOR MELTING PROCESSES OF SOLID ARTICLES IMMERSED IN METAL BATHS

B.K. Li , X.F. Ma , X.R. Zhang and J.C. He (Northeastern University , Shenyang 110006 , China)(Northeastern University , Shenyang 110006 , China)(Northeastern University , Shenyang 110006 , China)(Northeastern University , Shenyang 110006 , China)

金属学报(英文版)

A mathematical model for melting processes of solid particles immersed in metal baths has been develOPed, which includes the cases with the melting point of solid particles greater than, equal to, and lower than freezing point of the bath. Experiments are performed on the melting of ice spheres in water at different temperature. The model is validated by experimental data for melting of ice spheres submerged in water and aluminum spheres immersed in aluminum melt. Finally, the parometers affecting particles melting time such as particle size, bath temperature, and slip velocity are analyzed.

关键词: mathematical model; phase change; solid particle

AN UNIDENTIFIED MAGNETIC TRANSITION IN R2FE14X COMPOUNDS (R = SM, TB, DY, HO, ER, AND TM - X = B OR C)

Journal of Applied Physics

In Ho2Fe14B and Ho2Fe14C the temperature dependence of the ac initial susceptibility between 4.2 and 300 K shows two peaks. The peak at the lower temperature can be explained by a well-known spin reorientation transition (at 62 K for Ho2Fe14B and at 40 K for Ho2Fe14C). The peak at the higher temperature (at 245 K for Ho2Fe14B and at 265 K for Ho2Fe14C) disappears when the external field is applied parallel or perpendicular to the preferential direction of a magnetically aligned sample. The similar peak was also traced for R2Fe14X compounds (R = Sm, Tb, Dy, Ho, Er, and Tm; X = B or C). Searching for the nature of this peak traced by measuring the temperature dependence of the ac susceptibility for 3d-4f compounds is still under progress.

关键词:

Structure, phase transformation, and magnetic properties of R(16)Fe(76-x)Co(x)C(8) (R equivalent to Nd, Dy; 0 <= x <= 76) alloys prepared by a remilling process

Journal of Applied Physics

The effect of Co substitution on structure, phase transformation, and magnetic properties of R(16)Fe(76-x)Co(x)C(8) (R equivalent to Nd, Dy; 0 <= x <= 76) alloys prepared by a remilling process has been studied systematically. The process of remilling and subsequent annealing is more beneficial for the formation of Nd(2)(Fe,Co)(14)C compound in Nd(16)Fe(76-x)Co(x)C(8) alloys than in Dy(16)Fe(76-x)Co(x)C(8) alloys. The R(2)(Fe,Co)(14)C phase is obtained for Nd(16)Fe(76-x)Co(x)C(8) alloys with 0 <= x <= 20 and Dy(16)Fe(76-x)Co(x)C(8) alloys with 0 <= x <= 25. Higher Co content results in the formation of Nd(2)(Fe,Co)(17)C(delta)-type phase and Dy(Fe,Co)(7) phase for Nd(16)Fe(76-x)Co(x)C(8) and Dy(16)Fe(76-x)Co(x)C(8) alloys, respectively. The high coercivity, (i)H(c)=48.5 kOe, is achieved for Dy(16)Fe(51)Co(25)C(8) alloy. (C) 2008 American Institute of Physics.

关键词: permanent-magnets;r2fe14c;carbides;carbon

C掺杂对Al中He行为的影响

向鑫陈长安刘柯钊罗丽珠刘婷婷王小英

金属学报 doi:DOI:10.3724/SP.J.1037.2009.00590

用离子注入技术实现了Al表面C元素的掺杂, 并利用XPS, XRD, TEM和SEM研究了C掺杂对Al中离子
注入He行为的影响. 结果表明, 掺杂的C在Al表面形成了Al₄C₃, 随着C掺杂量的增加, Al表面组织的择优取向
和晶胞体积发生改变, 从而影响了Al中的He离子注入行为. 预先掺杂的C对He离子注入Al表面的鼓泡行为有重
要影响, 其影响程度与掺杂剂量有关. 小剂量C掺杂后, 能有效抑制鼓泡的长大, 并使Al表面鼓泡均匀分布; 更高
剂量C掺杂后, C对表面鼓泡的抑制作用减弱, 甚至加剧He离子的辐照损伤, Al表面出现孔洞和剥落现象. 掺杂的
C对Al基体的微观结构也有很大影响.

关键词: Al , C doping , He behavior , blistering , microstructure

C掺杂对Al中He行为的影响

向鑫 , 陈长安 , 刘柯钊 , 罗丽珠 , 刘婷婷 , 王小英

金属学报 doi:10.3724/SP.J.1037.2009.00590

用离子注入技术实现了Al表面C元素的掺杂,并利用XPS,XRD,TEM和SEM研究了C掺杂对Al中离子注入He行为的影响.结果表明,掺杂的C在Al表面形成了Al_4C_3,随着C掺杂量的增加,Al表面组织的择优取向和晶胞体积发生改变,从而影响了Al中的He离子注入行为,预先掺杂的C对He离子注入Al表面的鼓泡行为有重要影响,其影响程度与掺杂剂量有关,小剂量C掺杂后,能有效抑制鼓泡的长大,并使Al表面鼓泡均匀分布;更高剂量C掺杂后,C对表面鼓泡的抑制作用减弱,甚至加剧He离子的辐照损伤,Al表面出现孔洞和剥落现象,掺杂的C对Al基体的微观结构也有很大影响,

关键词: Al , C掺杂 , He行为 , 鼓泡 , 微观结构

EFFECT OF SPECIMEN SIZE ON J_R RESISTANCE CURVE

H.P. Chen and Z.J. Deng (State Key Lab. for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an 710049 , China)

金属学报(英文版)

The effect of specimen thinkness on JR resistance curve has been investigated using low and middle strength steels. As the J dominance regime is reached, the initial J-integral values, J(i), are definite even if the elastic component Ji(e) and plastic component Ji(p)vary with the thinkness of specimen. The wider the specimen width, the larger the Ji(e)/Ji and the smaller the Ji(p)/Ji. The crack propagation resistance, dJR/da and dJp/da, decreases, while dJe/da increases linearly with increasing specimen thinness.Based on the above experimental results, an empirical formula dJ/da = α+β. B is given, which can be used to evaluate the safety of practical structural components.A modified J-integral is presented, upon which a new view is Put forward that the increase in crack growth resistance is induced mainly by the increase in the plastic J-integral component with the crack propagation,

关键词: : fracture mechanics , null , null , null

关于动态钝化线方程与J-R法确定JId的讨论

杨卓青 , 刘瑞堂 , 周志方 , 尹建成

机械工程材料 doi:10.3969/j.issn.1000-3738.2006.03.006

在摆锤式示波冲击试验机上采用小角度冲击方法测试了某船用低合金钢的动态弹塑性断裂韧度JId.针对多试样J-R阻力曲线法因钝化线的不易确定性常造成测试结果JId误差较大的情况,考虑了加载速率对塑性流变应力的影响,给出了一新的动载条件下的钝化线方程:J=2NK(0.5εF)n△a.在J-R阻力曲线法测定材料的JId时,用该方程可得到与小角度冲击方法相一致的测试结果.

关键词: 动态钝化线 , 小角度冲击法 , J-R阻力曲线法 , 动态弹塑性断裂韧度JId

MAGNETIC-PROPERTIES OF R2CO14(B,C) COMPOUNDS (R = Y, SM)

Journal of Applied Physics

The magnetic properties of R2Co14B1-xCx (x=0, 0.5 and R=Y, Sm) compounds have been studied by measuring the temperature dependence of the easy- and hard-magnetization curves on magnetically aligned samples between 1.5 and 300 K for Y2Co14(B,C) and at 4.2 K for Sm2Co14(B,C). The magnetic anisotropy of Y2Co14B increases due to the substitution of C for B, whereas the saturation magnetization decreases. Between 1.5 and 300 K, the anisotropy field of Y2Co14B0.5C0.5 increases about 2 T and the Co moment decreases about 0.05mu(B). The anisotropy field Of Sm2Co14B also increases upon C substitution and the saturation magnetization decreases slightly. The ac susceptibilities of both SM2Co14B and Sm2Co14B0.5C0.5 exhibit anomalies that may arise from a spin reorientation within the basal plane.

关键词: nd2fe14b;exchange;nd2co14b;r2fe14b;field

NEUTRON DIFFRACTION STUDY ON R_2Fel_(17)N_x(R=Y,Dy,Nd)

YANG Jilian ZHANC Baisheng DINC Yongfan China Institute of Atomic Engergy , Beijing , ChinaYANG Yingchang ZHANG Xiaodong Peking University , Beijing , ChinaPAN Shuming General Research Institute for Non-Ferrous Metals , Beijing , China associate professor , P.O.Box 275 , Branch No.30 , Beijing 102413 , China

金属学报(英文版)

The N occupying sites and magnetic structures in R_2Fe_(17)N_x(R=Y,Dy,Nd)are de- termined by neutron diffraction.The effects of the site occupation of N on magnetic properties are discussed primarily.

关键词: neutron diffraction , null , null , null , null , null

XRD研究Fe、C掺杂对He离子注入Al表面晶各畸变的影响

向鑫 , 陈长安 , 蒋春丽

稀有金属材料与工程

用离子注入技术实现了Al表面Fe、C元素的掺杂,并用XRD研究Fe、C掺杂对He离子注入Al表面晶格畸变的影响.结果发现,预先掺杂的Fe、C在Al表面的晶格畸变中扮演重要角色,且影响程度与掺杂剂量有关.随着预先掺杂Fe剂量的增大,Al表面晶格畸变量先减小后增加,表明小剂量的Fe掺杂有助于降低He离子注入引起的晶格畸变.C掺杂后能进一步降低预先掺杂Fe引起的晶格畸变,降低程度随C剂量的增加而增加.可见,小剂量的Fe和高剂量的C共掺杂能有效降低He离子注入后Al表面的品格畸变.

关键词: Al , XRD , Fe、C掺杂 , 晶格畸变