G.P. Chen
,
T.R. Zhou
,
H. Yan
,
F.Y. Zhang
,
null
,
null
,
null
金属学报(英文版)
The effect of predeformation manner,
predeformation ratio and isothermal heat-treat parameter on the
non-dendrite structure of AZ61 magnesium alloy in SIMA process was
studied. Under coequal heat-treat condition, the impact of the hot
upsetting predeformation on semi-solid microstructure in SIMA
process was compared with that of the cold compressive
predeformation. The results indicate that non-dendrite
microstructure in AZ61 magnesium alloy billets can be obtained by
hot or cold upsetting predeformation in SIMA process, although their
mechanisms of evolution are different. Increasing hot or cold
upsetting predeformation ratio can enhance the effect and quality of
the non-dendrite microstructure formed before storage energy up to
saturation, but the proper isothermal temperature and holding time
should be selected.
关键词:
AZ61 magnesium alloy
,
null
材料科学技术（英文）
Structure and magnetostriction of Dy1-xPrxFe2 (0 less than or equal to x less than or equal to 0.5), Dy0.6Pr0.4(Fe1-yTy)(2) (0 less than or equal to y less than or equal to 0.6), and Tb1-zPrz(Fe0.4Co0.6)(2) (0 less than or equal to z less than or equal to 1.0) alloys (T=Co, Ni) have been investigated. It is found that the matrix of the alloys Dy1-xPrxFe2 is a single phase (Dy, Pr)Fe-2 with MgCu2-type structure and the second phase is (Dy, Pr)Fe-3 when x less than or equal to 0.2. The amount of (Dy, Pr)Fe-3 phase increases with increasing Pr content and becomes the main phase when x=0.4. The matrix of Dy1-xPrxFe2 is found to be the (Dy, Pr)(2)Fe-17 phase with Th2Zn17-type structure when x=0.5. It is found that the amount of the cubic Laves phase (Dy, Pr)(Fe, Co)(2) in the Dy0.6Pr0.4(Fe1-yCoy)(2) increases with increasing Co concentration when 0 less than or equal to y less than or equal to 0.6. The substitution of Ni for Fe is nearly not favorable for the formation of the cubic Laves phase (Dy, Pr)(Fe, Ni)(2) in (Dy1-xPrx)Fe-2. The matrix of (Tb1-zPrz)(Fe0.4Co0.6)(2) is a (Tb, Pr)(Fe, Co)(2) phase with the MgCu2-type cubic Laves structure and a second phase of small amount is (Tb, Pr)(Fe, Co)(3) phase when z less than or equal to 0.2, z=0.5 and 1.0. When 0.2
关键词:
Zhijun GUO
,
Zhidong ZHANG
,
Xinguo ZHAO
,
Bowen WANG
,
Dianyu GENG
材料科学技术（英文）
Structure and magnetostriction of Dy1-xPrxFe2 (0 less than or equal to x less than or equal to 0.5), Dy0.6Pr0.4(Fe1-yTy)(2) (0 less than or equal to y less than or equal to 0.6), and Tb1-zPrz(Fe0.4Co0.6)(2) (0 less than or equal to z less than or equal to 1.0) alloys (T=Co, Ni) have been investigated. It is found that the matrix of the alloys Dy1-xPrxFe2 is a single phase (Dy, Pr)Fe-2 with MgCu2-type structure and the second phase is (Dy, Pr)Fe-3 when x less than or equal to 0.2. The amount of (Dy, Pr)Fe-3 phase increases with increasing Pr content and becomes the main phase when x=0.4. The matrix of Dy1-xPrxFe2 is found to be the (Dy, Pr)(2)Fe-17 phase with Th2Zn17-type structure when x=0.5. It is found that the amount of the cubic Laves phase (Dy, Pr)(Fe, Co)(2) in the Dy0.6Pr0.4(Fe1-yCoy)(2) increases with increasing Co concentration when 0 less than or equal to y less than or equal to 0.6. The substitution of Ni for Fe is nearly not favorable for the formation of the cubic Laves phase (Dy, Pr)(Fe, Ni)(2) in (Dy1-xPrx)Fe-2. The matrix of (Tb1-zPrz)(Fe0.4Co0.6)(2) is a (Tb, Pr)(Fe, Co)(2) phase with the MgCu2-type cubic Laves structure and a second phase of small amount is (Tb, Pr)(Fe, Co)(3) phase when z less than or equal to 0.2, z=0.5 and 1.0. When 0.2
关键词:
陶光胤
,
王洪涛
,
王振杰
物理测试
文章利用简易的固相反应法制备了YBa2Cu3O(7-8)(YBCO)样品.利用FD-TX-RT-Ⅱ高温超导转变温度测定仪测试YBCO样品的超导临界温度Tc为90 K左右,并绘制了YBCO的R-T曲线和电镜图像.
关键词:
简易方法
,
YBCO
,
R-T研究
Journal of Magnetism and Magnetic Materials
Measuring the temperature dependence of the ac-initial susceptibility chi-ac (T) of Nd2Fe14B, two peaks were found. One peak, which is at 140 K, corresponds to the occurrence of the spin reorientation transition. The second one, which is at 220 K, can be correlated to the temperature where the FOMP (first order magnetization process) transition starts. A similar behaviour was found in Nd2Fe14C and Nd2Co14B also. Only one peak was detected for Pr2Fe14B and Pr2Co14B, suggesting that no spin reorientation but a FOMP does exist in these compounds. Direct measurements of the temperature dependence of the critical FOMP field and the anisotropy field using the SPD technique prove that this peak occurs due to the FOMP transition. A theoretical, however phenomenologically based, analysis gives an explanation for the occurrence of these peaks in chi-ac (T). Furthermore, it can be shown that the peak in the ac-initial susceptibility, which indicates the onset temperature of the FOMP, can be detected only by measuring either on polycrystalline samples or applying the external ac-field in some special crystallographic directions of a single crystalline sample. The peak which corresponds to the occurrence of a FOMP will disappear if the external ac-field is applied parallel to the c-axis or preferential axis of a magnetically oriented sample. This gives an opportunity to differentiate a peak due to a FOMP from that of a spin reorientation by ac-initial susceptibility measurements. It should be mentioned that this new and simple method gives the possibility to get direct information whether there exists a FOMP transition in a compound or not. This is especially important if a FOMP occurs at very high fields which are far beyond the limit of the current facilities. This allows also the experimental test of CEF calculations which predict sometimes a FOMP transition in high magnetic fields and the critical temperature range where high order CEF terms can or cannot be neglected.
关键词:
high-field magnetization;single-crystal nd2fe14b;anisotropy;r2fe14b;y2fe14b;dependence;exchange;pr2fe14b;r2co14b;alloys
Physical Review B
The spin-reorientation transition, magnetic anisotropy, and first-order magnetization process (FOMP) of R2Fe14BNx compounds with R = Pr or Nd have been investigated by ac-susceptibility measurements from 4.2 to 300 K, the singular-point-detection technique in a pulsed-field facility in fields up to 30 T between 4.2 and 500 K and magnetization measurements in the Amsterdam High-Field Installation in fields up to 35 T and 4.2 K. It is observed that, compared to the corresponding R2Fe14B compounds, the anisotropy field, B(a), and the critical field of the FOMP, B(cr), of R2Fe14BNx are dramatically reduced, whereas the spin-reorientation temperature T(SR), of Nd2Fe14BNx is only slightly decreased. These experimental data are analyzed in terms of the crystalline-electric-field interaction combined with the R-Fe exchange interaction.
关键词:
field magnetization measurements;single-crystals;nd2fe14b;transition;nitrides;pr2fe14b;series
