Formation of eutectic RuAl/Ru nanocomposite by mechanical alloying and subsequent annealing

2001 ◽  
Vol 16 (9) ◽  
pp. 2459-2462 ◽  
Author(s):  
K. W. Liu ◽  
F. Mücklich ◽  
R. Birringer
Keyword(s):  
Solid Solution ◽  
Differential Scanning Calorimetry ◽  
Mechanical Alloying ◽  
Heat Release ◽  
Eutectic Composition ◽  
Scanning Calorimetry ◽  
Powder Mixtures ◽  
Al Powder ◽  
Al Matrix ◽  
Milled Powders

No abrupt reaction was observed during mechanical alloying (MA) of Ru and Al powder mixtures with an eutectic composition (Ru70Al30). As-milled powders constitute mainly a Ru(Al) solid solution and/or mixture (matrix), and a very small quantity of RuAl. The complete reaction between Ru and Al during MA was speculated to be hampered by excess Ru in Ru70Al30. No exothermic heat release was detected in differential scanning calorimetry for as-milled powders. Precipitation of RuAl from as-milled Ru(Al) matrix was observed after annealing at various temperatures. The phase fraction of Ru and RuAl reaches an approximately equilibrium value after annealing at 1173 K.

The synthesis of NbSi2 by mechanical alloying

1997 ◽  
Vol 12 (5) ◽  
pp. 1172-1175 ◽  
Author(s):  
Taiping Lou ◽  
Guojiang Fan ◽  
Bingzhe Ding ◽  
Zhuangqi Hu
Keyword(s):  
Solid Solution ◽  
Differential Scanning Calorimetry ◽  
Intermetallic Compound ◽  
Mechanical Alloying ◽  
Ball Milling ◽  
Temperature Rise ◽  
Milling Time ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray

The stoichiometric intermetallic compound NbSi2 has been synthesized by mechanical alloying (MA) elemental Nb and Si powders. The alloying process has been investigated by means of x-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was found that the formation of the Nb2Si intermetallic compound occurs abruptly after 65 min of milling without any interruptions during the alloying process. However, short interruptions at a 5 min interval during ball milling result in a gradual reaction for the formation of the NbSi2 compound as well as a new metastable bcc structured solid solution. We conclude that the temperature rise during mechanical alloying plays an important role in initiating the abrupt reaction after an incubation milling time.

Compatibility between Magnesium Stearate and Pharmaceutical Acidic Active Compounds/Excipients with DSC

2020 ◽  
Vol 856 ◽  
pp. 190-197
Author(s):  
Pornsit Chaiya ◽  
Thawatchai Phaechamud
Keyword(s):  
Differential Scanning Calorimetry ◽  
Magnesium Stearate ◽  
X Ray Diffraction ◽  
Salt Form ◽  
Scanning Calorimetry ◽  
Powder Mixtures ◽  
X Ray ◽  
Pharmaceutical Excipients ◽  
Drug Compounds ◽  
Ft Ir

Compatibility investigation was performed between magnesium stearate and acidic drug compounds (ibuprofen, indomethacin and valproic acid) and acidic pharmaceutical excipients (lactic acid and citric acid) using differential scanning calorimetry (DSC). DSC study indicated the possible incompatibility for the mixture between magnesium stearate and any compounds. Alteration in DSC thermogram was found in all mixtures. The eutectic phenomenon was found in the powder mixture of magnesium stearate and ibuprofen. In addition, the presence of melting endothermic peak of stearic acid in other powder mixtures except the mixture of magnesium stearate and indomethacin indicating breakage of salt form of magnesium stearate. This alteration could relate to the influence on physicochemical properties of drug compounds and pharmaceutical excipients which powder x-ray diffraction (PXRD) and Fourier Transform Infrared Spectroscopy (FT-IR) should be further analyzed to confirm the interactions between compounds.

The formation of metastable Ti–Al solid solutions by mechanical alloying and ball milling

1993 ◽  
Vol 8 (11) ◽  
pp. 2819-2829 ◽  
Author(s):  
M. Oehring ◽  
T. Klassen ◽  
R. Bormann
Keyword(s):  
Solid Solution ◽  
Mechanical Alloying ◽  
Ball Milling ◽  
Intermetallic Compounds ◽  
Phase Formation ◽  
Milling Process ◽  
Study Phase ◽  
Phase Selection ◽  
Powder Blends ◽  
Al Powder

Elemental Ti–Al powder blends were mechanically alloyed in order to study phase formation during the alloying process. In addition, the stability of intermetallic phases upon milling was investigated separately in order to determine the origins of phase selection during the milling process. It was found that by mechanical alloying of powder blends, as well as by ball milling of Ti-aluminides for long milling times, the same metastable phases were formed for corresponding compositions, i.e., the hep solid solution for Al concentrations up to 60 at. % and the fcc solid solution for 75 at. % Al. X-ray diffraction (XRD) analyses indicated that the process of mechanical alloying occurred via the diffusion of Al into Ti. By lowering the milling intensity, a two-phase mixture of the hcp solid solution and the amorphous phase was observed for Ti50Al50 and confirmed by transmission electron microscopy (TEM). The results show that phase selection in the final state during mechanical alloying of Ti–Al powder blends and milling of intermetallic compounds is mainly determined by the energetic destabilization of the competing phases caused by the milling process. The destabilization is most pronounced in the case of intermetallic compounds due to the decrease in long-range order upon milling. For the final milling stage, phase formation can be predicted by considering the relative stabilities of the respective phases calculated by the CALPHAD method using the available thermodynamic data for the Ti–Al system.

scholarly journals Mechanical Alloying of Ti–Al Powder Mixtures under Nitrogen Atmosphere

1993 ◽  
Vol 34 (10) ◽  
pp. 952-959 ◽  
Author(s):  
Masamichi Miki ◽  
Tohru Yamasaki ◽  
Yoshikiyo Ogino
Keyword(s):  
Mechanical Alloying ◽  
Nitrogen Atmosphere ◽  
Powder Mixtures ◽  
Al Powder

Thermal Stability of Amorphous Ti- Cu- Ni- Sn Prepared by Mechanical Alloying

2007 ◽  
Vol 534-536 ◽  
pp. 233-236 ◽  
Author(s):  
N.T.H. Oanh ◽  
Pyuck Pa Choi ◽  
Ji Soon Kim ◽  
Dae Hwan Kwon ◽  
Young Soon Kwon
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Mechanical Alloying ◽  
Amorphous Alloys ◽  
High Energy ◽  
Scanning Calorimetry ◽  
Thermal Stability Of

Ti-Cu-Ni-Sn quaternary amorphous alloys of Ti50Cu32Ni15Sn3, Ti50Cu25Ni20Sn5, and Ti50Cu23Ni20Sn7 composition were prepared by mechanical alloying in a planetary high-energy ballmill (AGO-2). The amorphization of all three alloys was found to set in after milling at 300rpm speed for 2h. A complete amorphization was observed for Ti50Cu32Ni15Sn3 and Ti50Cu25Ni20Sn5 after 30h and 20h of milling, respectively. Differential scanning calorimetry analyses revealed that the thermal stability increased in the order of Ti50Cu32Ni15Sn3, Ti50Cu25Ni20Sn5, and Ti50Cu23Ni20Sn7.

Study on the Precipitation Sequence of Aged NCu30-4-2-1 Alloy by DSC

2014 ◽  
Vol 1061-1062 ◽  
pp. 35-38
Author(s):  
Yun Long Ai ◽  
Xiao Rui Shen ◽  
Wei Hua Chen ◽  
Yao Hui Xie
Keyword(s):  
Solid Solution ◽  
Differential Scanning Calorimetry ◽  
Supersaturated Solid Solution ◽  
Aging Treatment ◽  
Holding Time ◽  
Precipitation Sequence ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Different Temperatures ◽  
Block Distribution

NCu30-4-2-1 alloy was handled by solid solution at 950°Cfor 2h and then taking aging treatment at different temperatures and holding time. The microstructural evolution of NCu30-4-2-1 alloy in the process of aging treatment was investigated by metallographic microscope, X-ray diffractometer and differential scanning calorimetry. The results show that the phases of as-cast NCu30-4-2-1 alloy is composed by dendritic α-Ni-based solid solution and β-Ni3Si. After solid solution and aging treatment, the block distribution β-Ni3Si dissolves and many small granular dispersed distribution β'-Ni3Si precipitate out. With the increase of aging temperature and holding time, metastable β' tends to transform into stable β-Ni3Si. The precipitation sequence of aged NCu30-4-2-1alloy is supersaturated solid solution of α-Ni, GP zone, β'-Ni3Si and β-Ni3Si.

scholarly journals Теплоемкость твердых растворов системы Er-=SUB=-2-=/SUB=-Ge-=SUB=-2-=/SUB=-O_7- Er-=SUB=-2-=/SUB=-Sn-=SUB=-2-=/SUB=-O-=SUB=-7-=/SUB=- в области 350-1000 K

2019 ◽  
Vol 61 (4) ◽  
pp. 660
Author(s):  
Л.Т. Денисова ◽  
Л.А. Иртюго ◽  
В.В. Белецкий ◽  
Н.В. Белоусова ◽  
В.М. Денисов
Keyword(s):  
Solid Solution ◽  
Differential Scanning Calorimetry ◽  
Solid State ◽  
Specific Heat ◽  
Solid Solutions ◽  
Thermodynamic Functions ◽  
Solution Composition ◽  
Scanning Calorimetry ◽  
Solid Solution Composition ◽  
Effects Of Temperature

AbstractEr_2Ge_2O_7–Er_2Sn_2O_7 solid solutions have been obtained using solid-state synthesis by burning the stoichiometric mixtures of the initial oxides in air in the temperature range of 1273–1473 K. The effects of temperature and solid solution composition on the specific heat have been examined by differential scanning calorimetry. The Er_2Ge_2O_7 thermodynamic functions have been calculated.

scholarly journals Miscibility and Solubility of Caffeine and Theophylline in Hydroxypropyl Methylcellulose

Pharmaceutics ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1836
Author(s):  
Edyta Leyk ◽  
Marek Wesolowski
Keyword(s):  
Solid Solution ◽  
Differential Scanning Calorimetry ◽  
Hydroxypropyl Methylcellulose ◽  
Theoretical Data ◽  
Principal Component ◽  
Scanning Calorimetry ◽  
Amorphous Phases ◽  
Chemical Structures ◽  
Physical Mixtures ◽  
Ftir And Raman Spectroscopy

As amorphization may improve the solubility and bioavailability of a drug substance, the aim of this work was to assess to what extent the crystallinity of caffeine (CAF) and theophylline (TF) can be reduced by homogenization with a polymeric excipient. To realize this purpose, the physical mixtures of both methylxanthines with hydroxypropyl methylcellulose (HPMC) were examined using differential scanning calorimetry (DSC), hot-stage microscopy (HSM), Fourier-transform infrared (FTIR) and Raman spectroscopy. Moreover, phase diagrams for the physical mixtures were calculated using theoretical data. Results of DSC experiments suggested that both CAF and TF underwent amorphization, which indicated proportional loss of crystallinity for methylxanthines in the mixtures with HPMC. Additionally, HSM revealed that no other crystalline or amorphous phases were created other than those observed for CAF and TF. FTIR and Raman spectra displayed all the bands characteristic for methylxanthines in mixtures with HPMC, thereby excluding changes in their chemical structures. However, changes to the intensity of the bands created by hydrogen bonds imply the formation of hydrogen bonding in the carbonyl group of methylxanthines and the methyl polymer group. This is consistent with data obtained using principal component analysis. The findings of these studies revealed the quantities of methylxanthines which may be dissolved in the polymer at a given temperature and the composition at which methylxanthines and polymer are sufficiently miscible to form a solid solution.

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