The crystallization behaviour of a-Pd_(80)Si_(20) in the high temperature internal friction peak region is systematically studied by DSC and X-ray diffraction techniques.
Nano-crystalline elemental iron powder was successfully formed by high-energy ball grinding.The x-ray diffraction,transmission electron microscopy and Mdssbauer spectroscopy were employed to follow the structure chang...Nano-crystalline elemental iron powder was successfully formed by high-energy ball grinding.The x-ray diffraction,transmission electron microscopy and Mdssbauer spectroscopy were employed to follow the structure changes in the process of mechanical grinding with milling time.The thermal stability of nanocrystalline iron powder was also studied by differential scanning calorimetry.The results showed that the grain size reduces drastically at the initial stage of the milling and reaches 6nm after 40h milling.The broadening of Mdssbauer spectrum is attributed to the large fraction of iron atoms existing at the interfaces for the powder milled.展开更多
Amorphization of Cu-Zr and Ni-Zr systems by mechanical alloying(MA)was studied by X-ray diffraction.The results show that the amorphization is not merely a simple interdiffusion by thermal activation;in addition,the s...Amorphization of Cu-Zr and Ni-Zr systems by mechanical alloying(MA)was studied by X-ray diffraction.The results show that the amorphization is not merely a simple interdiffusion by thermal activation;in addition,the strain induced by MA also accelerates this process.展开更多
Effect of hydrolysis catalysts(HCl and C_(5)H_(8)O_(2))on structural evaluation of gelderived nanocrystalline TiO_(2) powders was studied.Crystallization temperature of the HCl catalyzed gel is about 200K lower than t...Effect of hydrolysis catalysts(HCl and C_(5)H_(8)O_(2))on structural evaluation of gelderived nanocrystalline TiO_(2) powders was studied.Crystallization temperature of the HCl catalyzed gel is about 200K lower than that of the C_(5)H_(8)O_(2) catalyzed one.But in the later gel the anatase phase transforms to rutile at a lower temperature,and the transformation is completed in a much more narrow temperature range.展开更多
Enthalpy relaxation in amorphous Pd_(77.5) Cu_(6.0)Si_(16.5) in sub-Tg temperature region was studied by differential scanning calorimetry(DSC).Enthalpy change due to annealing,which was measured by deducting the effe...Enthalpy relaxation in amorphous Pd_(77.5) Cu_(6.0)Si_(16.5) in sub-Tg temperature region was studied by differential scanning calorimetry(DSC).Enthalpy change due to annealing,which was measured by deducting the effect of glass transition,increased gradually to a saturated value with increasing annealing time(ta).At lower temperatures,enthalpy relaxation exhibited two-stage in ta dependence.展开更多
During structural relaxation of a glassy matrix,the apparent internal friction(Q^(-1))decreased with the increase of annealing time(t).The dependence of Q^(-1) on t can be shown as Q^(-1)=At^(-β)+B,where A,B andβare...During structural relaxation of a glassy matrix,the apparent internal friction(Q^(-1))decreased with the increase of annealing time(t).The dependence of Q^(-1) on t can be shown as Q^(-1)=At^(-β)+B,where A,B andβare constants.展开更多
The effect of neutron-irradiation on crystallization of Cu-Ti glasses of four compositions was systematically studied by differential scanning calorimetry(DSC)and internal friction measurements.The results show that t...The effect of neutron-irradiation on crystallization of Cu-Ti glasses of four compositions was systematically studied by differential scanning calorimetry(DSC)and internal friction measurements.The results show that the susceptibility of the glasses to irradiation is quite composition dependent.展开更多
文摘The crystallization behaviour of a-Pd_(80)Si_(20) in the high temperature internal friction peak region is systematically studied by DSC and X-ray diffraction techniques.
基金Supported by the National Natural Science Foundation of China。
文摘Nano-crystalline elemental iron powder was successfully formed by high-energy ball grinding.The x-ray diffraction,transmission electron microscopy and Mdssbauer spectroscopy were employed to follow the structure changes in the process of mechanical grinding with milling time.The thermal stability of nanocrystalline iron powder was also studied by differential scanning calorimetry.The results showed that the grain size reduces drastically at the initial stage of the milling and reaches 6nm after 40h milling.The broadening of Mdssbauer spectrum is attributed to the large fraction of iron atoms existing at the interfaces for the powder milled.
基金Project supported by National Science Foundation of China。
文摘Amorphization of Cu-Zr and Ni-Zr systems by mechanical alloying(MA)was studied by X-ray diffraction.The results show that the amorphization is not merely a simple interdiffusion by thermal activation;in addition,the strain induced by MA also accelerates this process.
文摘Effect of hydrolysis catalysts(HCl and C_(5)H_(8)O_(2))on structural evaluation of gelderived nanocrystalline TiO_(2) powders was studied.Crystallization temperature of the HCl catalyzed gel is about 200K lower than that of the C_(5)H_(8)O_(2) catalyzed one.But in the later gel the anatase phase transforms to rutile at a lower temperature,and the transformation is completed in a much more narrow temperature range.
文摘Enthalpy relaxation in amorphous Pd_(77.5) Cu_(6.0)Si_(16.5) in sub-Tg temperature region was studied by differential scanning calorimetry(DSC).Enthalpy change due to annealing,which was measured by deducting the effect of glass transition,increased gradually to a saturated value with increasing annealing time(ta).At lower temperatures,enthalpy relaxation exhibited two-stage in ta dependence.
文摘During structural relaxation of a glassy matrix,the apparent internal friction(Q^(-1))decreased with the increase of annealing time(t).The dependence of Q^(-1) on t can be shown as Q^(-1)=At^(-β)+B,where A,B andβare constants.
基金supported by the National Science Fund of China。
文摘The effect of neutron-irradiation on crystallization of Cu-Ti glasses of four compositions was systematically studied by differential scanning calorimetry(DSC)and internal friction measurements.The results show that the susceptibility of the glasses to irradiation is quite composition dependent.
文摘目的分析1例白血病患者人类白细胞抗原(human leukocyte antigen,HLA)杂合性丢失情况。方法采用聚合酶链反应序列特异性寡核苷酸探针法和聚合酶链反应测序方法对患者移植后外周血、头发毛囊、口腔黏膜拭子及其父母外周血进行HLA分型。采用23位点短串联重复序列(short tandem repeat,STR)测定试剂盒和本实验室建立的HLA区域内的6个STR位点方法对患者移植后的外周血、口腔黏膜拭子及其父母外周血进行STR位点检测。结果患者经父亲源单倍型造血干细胞移植后,外周血标本HLA基因型与父亲完全一致。患者头发毛囊标本HLA结果为HLA-A*02:01,24:02,C*03:03,03:04,B*13:01,15:01,DRB1*08:03,12:02,DQB1*03:01,06:01。口腔黏膜拭子为HLA纯合子,只存在父亲单倍型HLA-A*24:02-C*03:03-B*15:01-DRB1*08:03-DQB1*06:01,丢失了母亲单倍型HLA-A*02:01-C*03:04-B*13:01-DRB1*12:02-DQB1*03:01。患者移植后外周血23个STR位点与父亲完全一致。口腔黏膜拭子23位点短串联重复位点无丢失,但6号染色体上HLA区域的6个STR位点至少有4个发生了丢失。结论发现1例单倍型造血干细胞移植白血病患者的口腔黏膜拭子发生HLA杂合性丢失。
