利用金相和 SEM 显微组织分析技术,示差扫描量热法(DSC)和振动磁力计(VSM)考察了 Ni_(52)Ga_(28)Fe_(20-x)Co_x 合金中 Co 元素含量 x 对马氏体相变和铁磁性转变的影响,用粉末 X 射线衍射方法(XRD)分析马氏体相的结构类型．在x(?)6 的...利用金相和 SEM 显微组织分析技术,示差扫描量热法(DSC)和振动磁力计(VSM)考察了 Ni_(52)Ga_(28)Fe_(20-x)Co_x 合金中 Co 元素含量 x 对马氏体相变和铁磁性转变的影响,用粉末 X 射线衍射方法(XRD)分析马氏体相的结构类型．在x(?)6 的范围内 Co 代替 Fe 能够显著提高 Ni_(52)Ga_(28)Fe_(20-x)Co_x 合金的马氏体相变温度,对铁磁性转变 Curie 点的影响不大．x 每增加1可以使马氏体相变温度提高50—60K．低温淬火(773K/1h)对 Ni_(52)Ga_(28)Fe_(20-x)Co_x 合金马氏体相变温度的影响不大,但使合金的 Curie 点提高20—30 K．粉末 XRD 分析表明该合金系列经1423和773K 两种温度处理后都只出现 L1_0(2M)马氏体．展开更多
Ferromagnetic shape memory alloys （FSMAs） such as NiMnGa, FePd and FePt are attractive as a new magnetic actuator material. They show a large magnetic-field-induced strain of 3% 9% due to the variant rearrangement. ...Ferromagnetic shape memory alloys （FSMAs） such as NiMnGa, FePd and FePt are attractive as a new magnetic actuator material. They show a large magnetic-field-induced strain of 3% 9% due to the variant rearrangement. Recently, the present authors have reported that in the Ni-Ga-Fe alloy the martensitic transformationfrom the B2 and/or the L21 structures into a seven-layer or five-layer modulated structure occurs upon cooling. In this alloy system, however, it is impossible to obtain a martensite phase at RT with a Curie temperature （TC） higher than 100 ℃. In this work,the effects of substitution of Co for Ni on the martensitic and magnetic transformations,crystal structures and phase equilibria in Ni-Ga-Fe alloys were studied.Ni-Ga-Fe-Co alloys were prepared by induction melting under an argon atmosphere.Small pieces of specimens were taken from the ingot and homogenized at 1433 K for 24 h followed by quenching in water. The obtained specimens were aged at 773 K for 24 h and then quenched. The compositions of each phase were determined by energy dispersion X-ray spectroscopy （EDX）. The martensitic transformation temperatures and TC were measured by differential scanning calorimetry （DSC） and vibrating sample magnetometer （VSM） measurement. The crystal structure of martensite phase was observed by X-ray diffractmeter （XRD） and transmission electron microscope （TEM）.The Curie temperature TC was increased with increasing Co content while the martensitic transformation temperature slightly decreased. In the Ni<sup>54-x Ga<sup>27 Fe<sup>19 Cox ,TC increases from 303 K to 408 K with increasing Co content from x=0 to x=6. The crystal structure of the martensite phase and the phase equiribria in the Ni-Fe-Ga-Co alloys will be also presented.展开更多
A series of M-substituted hexaaluminates LaMAl11O19-δ （M=Fe, Co, Ni, Mn, and Cu） were prepared and characterized by XRD, XPS, TPR and TGA techniques, respectively. They exhibited different reducibility and catalyti...A series of M-substituted hexaaluminates LaMAl11O19-δ （M=Fe, Co, Ni, Mn, and Cu） were prepared and characterized by XRD, XPS, TPR and TGA techniques, respectively. They exhibited different reducibility and catalytic activity for partial oxidation of methane （POM） to synthesis gas. Among the LaMAl11019-δ samples, LaNiAl11O19-δ showed the best catalytic activity for the topic reaction and selectivity for synthesis gas at 780 ℃ for 2 h. The conversion of CH4 was over 99.2%, and the product selectivity for both CO and H2 was above 90.3%.展开更多
文摘利用金相和 SEM 显微组织分析技术,示差扫描量热法(DSC)和振动磁力计(VSM)考察了 Ni_(52)Ga_(28)Fe_(20-x)Co_x 合金中 Co 元素含量 x 对马氏体相变和铁磁性转变的影响,用粉末 X 射线衍射方法(XRD)分析马氏体相的结构类型．在x(?)6 的范围内 Co 代替 Fe 能够显著提高 Ni_(52)Ga_(28)Fe_(20-x)Co_x 合金的马氏体相变温度,对铁磁性转变 Curie 点的影响不大．x 每增加1可以使马氏体相变温度提高50—60K．低温淬火(773K/1h)对 Ni_(52)Ga_(28)Fe_(20-x)Co_x 合金马氏体相变温度的影响不大,但使合金的 Curie 点提高20—30 K．粉末 XRD 分析表明该合金系列经1423和773K 两种温度处理后都只出现 L1_0(2M)马氏体．
文摘Ferromagnetic shape memory alloys （FSMAs） such as NiMnGa, FePd and FePt are attractive as a new magnetic actuator material. They show a large magnetic-field-induced strain of 3% 9% due to the variant rearrangement. Recently, the present authors have reported that in the Ni-Ga-Fe alloy the martensitic transformationfrom the B2 and/or the L21 structures into a seven-layer or five-layer modulated structure occurs upon cooling. In this alloy system, however, it is impossible to obtain a martensite phase at RT with a Curie temperature （TC） higher than 100 ℃. In this work,the effects of substitution of Co for Ni on the martensitic and magnetic transformations,crystal structures and phase equilibria in Ni-Ga-Fe alloys were studied.Ni-Ga-Fe-Co alloys were prepared by induction melting under an argon atmosphere.Small pieces of specimens were taken from the ingot and homogenized at 1433 K for 24 h followed by quenching in water. The obtained specimens were aged at 773 K for 24 h and then quenched. The compositions of each phase were determined by energy dispersion X-ray spectroscopy （EDX）. The martensitic transformation temperatures and TC were measured by differential scanning calorimetry （DSC） and vibrating sample magnetometer （VSM） measurement. The crystal structure of martensite phase was observed by X-ray diffractmeter （XRD） and transmission electron microscope （TEM）.The Curie temperature TC was increased with increasing Co content while the martensitic transformation temperature slightly decreased. In the Ni<sup>54-x Ga<sup>27 Fe<sup>19 Cox ,TC increases from 303 K to 408 K with increasing Co content from x=0 to x=6. The crystal structure of the martensite phase and the phase equiribria in the Ni-Fe-Ga-Co alloys will be also presented.
基金This work was supported by the Education Department of Jilin Province and Science and Technology office of Siping Municipality.
文摘A series of M-substituted hexaaluminates LaMAl11O19-δ （M=Fe, Co, Ni, Mn, and Cu） were prepared and characterized by XRD, XPS, TPR and TGA techniques, respectively. They exhibited different reducibility and catalytic activity for partial oxidation of methane （POM） to synthesis gas. Among the LaMAl11019-δ samples, LaNiAl11O19-δ showed the best catalytic activity for the topic reaction and selectivity for synthesis gas at 780 ℃ for 2 h. The conversion of CH4 was over 99.2%, and the product selectivity for both CO and H2 was above 90.3%.
