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Dive into the research topics where M. S. Mostafa is active.

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Featured researches published by M. S. Mostafa.


Journal of Thermal Analysis and Calorimetry | 2004

INVESTIGATION OF THERMAL PROPERTIES OF SOME BASALT SAMPLES IN EGYPT

M. S. Mostafa; N. Afify; A. Gaber; E. F. Abu Zaid

This work aims in studying the temperature dependence of the thermal properties (thermal diffusivity, k, specific heat, Cp and thermal conductivity, λ) of some basalt group samples, collected from different regions in the eastern desert of Egypt. The thermal properties of these samples were measured in the temperature range from r.t. to 900 K. The average values of the thermal conductivity of these investigated samples lie in the range from 0.4·10−3 to 2.01·10−3 cal cm−1 s−1 K−1. This means that these samples are considered as thermal insulating materials. The thermogravimetric analysis (TG) confirmed that these investigated samples are dry rocks. X-ray fluorescence (XRF) and X-ray diffraction (XRD) confirmed that these rock samples have a crystalline phase, the peaks of XRD have a small change in their location as a result of heat treatment. This behaviour was attributed to the oxidation and firing of some minerals after the heat treatment.


Journal of Physics D | 1990

Investigation of the precipitation process in Al-Si alloys

A. Gaber; N. Afify; M. S. Mostafa

The early stage of clustering and the subsequent precipitation of Si atoms in Al+1.37, Al+2.83 and Al+6.81 at.% Si alloys have been investigated by means of electrical resistivity and microhardness measurements. The results showed that: (i) the interaction between the vacancy-type dislocations and the partially precipitated Si atoms is the predominant process during the initial stage (25-150 degrees C); (ii) as the large particles of Si precipitates are formed, they become no longer coherent with the Al matrix; (iii) the microhardness of the as-quenched specimens was found to increase linearly with increasing Si concentration in the alloy.


Solid State Communications | 1993

Electrical and microhardness studies on AlMg alloys

A. Gaber; N. Afify; A.Y. Abdel-Latief; M. S. Mostafa

The effect of Mg content on some of the electrical parameters and the microhardness of AlMg alloys has been investigated. Namely, the dependence of the temperature coefficient of resistivity, αall, the electronic relaxation time, τall, and the electron-impurity scattering power, Δν, on the Mg content in the alloys has been studied. On the other hand, the influence of dissolved Mg on the microhardness of AlMg alloys has been evaluated. In addition, the decomposition behaviour of the supersaturated AlMg alloys has been followed and characterized.


Journal of Alloys and Compounds | 1997

Characterization of the transport processes in FeCrNi stainless steel

N. Afify; A. Gaber; M. S. Mostafa; A.A. Hussein

Abstract Measurements of electrical resistivity, X-ray diffraction and DTA were used to characterize the transport processes developed in an Fe-12.1 Cr-7.37 Ni (wt.%) stainless steel during heating from 300 to 980 K and subsequently during cooling to room temperature. The results revealed that this steel exhibits two transport regions during heating and only one during cooling. In case of heating, the first transition region (observed in the temperature range 650–730 K) is not to a structural but may be a magnetic transition. The second transition region (observed in the temperature range 885–915 K) is ascribed to the austenitic structural transformation. During cooling, a unique transition region was observed in the range 560-434 K. This was attributed to the martensitic transformation which may also be associated with a magnetic transition. From the DTA data, the effective activation energy for the austenitic transformation was determined to be 459.3 kJ mol −1 . In the temperature ranges other than the transition regions the electrical resistivity fits a linear equation rather than the Bloch-Gruneisen equation.


Materials Science and Technology | 2002

Study of electrical and thermal properties of Al100-xLix

A. Gaber; N. Afify; M. S. Mostafa; S. Bin Anooz

Abstract The present work is a study of the electrical resistivity and thermal properties during continuous heating from room temperature up to 773 K of Al100x Lix (x=0·5, 1, 2, 3, 6, and 8) alloys. From the electrical resistivity measurements at room temperature it is concluded that the resistivity increment of Al—Li alloys (in solid solution state) is proportional to the fractional constituents (Li and Al) as Δρall [νX cm]=94·10±0·13 [νX cm] c(1c). In addition both the temperature coefficient of resistivity αall and the relaxation time of the free electrons τall of the alloys diminish with increasing the solute Li concentration. Using the measured variation of the specific heat C p and thermal diffusivity a as a function of temperature, the precipitation processes can be followed. Both tools were found to be sensitive for precipitation evolution.


Journal of Thermal Analysis and Calorimetry | 1995

Temperature dependence of the thermophysical properties of Bi1.5Sb0.5Te3

M. S. Mostafa; M. M. Wakkad; A. Gaber; N. Afify

The thermophysical properties (thermal diffusivitya, specific heatCp and thermal conductivity λ), of Bi1.5Sb0.5Te3 were measured in the temperature range 300–700 K. The results showed that the contribution of the charge carriers to the thermal conduction is negligibly small in comparison with the contribution of phonons at high temperatures. On the other hand, the heat conduction due to the simultaneous thermal diffusion of electrons and holes is important as well as the lattice thermal conduction. The explanation of the results was supported by using electrical conductivity measurements and X-ray diffraction.ZusammenfassungIm Temperaturintervall 300–700 K wurden die thermophysikalischen Eigenschaften (Temperaturleitvermögena, spezifische WärmeCp, und die Wärmeleitfähigkeit λ) von Bi1.5Sb0.5Te3 vermessen. Die Ergebnisse zeigen, daß der Beitrag der Ladungsträger zur thermischen Leitung im Vergleich zum Beitrag von Phononen bei höheren Temperaturen vernachlässigbar gering ist. Andererseits ist die Wärmeleitung infolge der simultanen thermischen Diffusion von Elektronen und Löchern genauso wichtig wie die Gitter-Wärmeleitung. Die Deutung der Ergebnisse wurde durch Anwendung von Messungen der elektrischen Leitfähigkeit und durch Röntgendiffraktion bestätigt.


Journal of Thermal Analysis and Calorimetry | 1989

Study of thermal properties of endellite clay compound

M. S. Mostafa; A. Gaber

The temperature dependence of the thermal properties (specific heat,Cp, thermal diffusivity,a, and thermal conductivity,K) of endellite clay has been investigated over the temperature rangeR·T⩽T≲/280 °C using the plane temperature wave technique. The experimental results showed that in the initial stage of temperature rise botha andK diminish exponentially with increasing temperature up to ∼100 °C. Above 100 °C, the thermal parameters are found to reach stable values, namely,Cp=0.22±0.008 cal g−1 deg−1,a=(5.0±0.18)−10−4 cm2 sec− 1 andK=(2.2±0.16) · 10−4 cal cm−1 sec−1 deg−1. The explanation of the results was supported by using DTA and TG analysis.ZusammenfassungIn einem Temperaturbereich zwischen Raumtemperatur und 280 °C wurde die Temperaturabhängigkeit der thermischen Eigenschaften (spezifische WärmeCp, Temperaturleitfähigkeita, WärmeleitfähigkeitK) von Endellittonerde untersucht. Die Ergebnisse zeigen, daß sowohla als suchK im ersten Abschnitt der Temperaturzunahme mit steigender Temperatur bis 100 °C exponentiell abnehmen. Oberhalb 100 °C erreichen die Parameter stabile Werte:Cp=0,22 ±0,008 cal g−1 deg−1,a=(5,0±0,18)·10−4 cm2 sec−1 undK=(2,2±0,16)·10−4 cal cm−1 sec−1 deg−1. Die Erklärung der Ergebnisse wurde unter Zuhilfenahme von DTA und TG durchgeführt.РезюмеМетодом плоской темп ературной волны изуч ена температурная завис имость термических свойств (удельная теплоемкос ть Сp, термический коэффиц иент диффузии и и термопроводимость К) глины энделлит в обла сти температур комнатна я температура ⩽T⩽280°. Экспериментальн ые результаты показа ли, что на начальной стадии под нятия температуры до 100° обе в еличины а и K экспоненц иально уменьшаются. Выше 100° те рмические параметры достигают постоянных значений равным Сn=О,22 ±0,008 кал · г−1· град−1, а=5,0±0,18·10−4 см2· сек−1 и K=2,2±0,16· 10−4 кал · см−1· сек−1· град−1. Обсуждение ре зультатов подтверждено ДТА и ТГ измерениями.


Journal of Alloys and Compounds | 2007

Precipitation kinetics of Al–1.12 Mg2Si–0.35 Si and Al–1.07 Mg2Si–0.33 Cu alloys

A. Gaber; M. A. Gaffar; M. S. Mostafa; E. F. Abo Zeid


High Temperatures-high Pressures | 2002

Phase transformation kinetics during the heating of an Al-8 at% Li alloy

N. Afify; A. Gaber; M. S. Mostafa; Saud Bin Anooz


Journal of Alloys and Compounds | 2007

Precipitation kinetics of Al1.12 Mg 2Si0.35 Si and Al1.07 Mg 2Si0.33 Cu alloys

Abd El-Aal M. Gaber; Mohammed A. Gaffar; M. S. Mostafa; E. F. Abo Zeid

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