mechanical alloying

At the present study, the mechanical alloying method was used to produce the nanocrystalline Cu-5Ta alloy. In order to achieve a specimen with desirable properties, effects of size of milling ball, atmosphere and temperature of sintering were investigated on crystalline More

At the present study, the mechanical alloying method was used to produce the nanocrystalline Cu-5Ta alloy. In order to achieve a specimen with desirable properties, effects of size of milling ball, atmosphere and temperature of sintering were investigated on crystalline structure, electrical conduction and microhardness of specimen. The microstructural studies indicated that a finer crystallite size was attained when the complex size of milling balls being composed of 10 and 5 millimeters was applied rather than simple one of 10 millimeters. After milling, cold press and subsequent sintering were done under different atmospheres such as nitrogen, argon and vacuum at temperature of 550C. The sintered specimen under vacuum showed the better properties compared to the others. The further evaluations on specimen properties was conducted by sintering at temperatures of 700 and 850C under vacuum. The results indicated that with increasing the sintering temperature, electrical conduction and microhardness increase. Overall, the specimen milled by the complex ball size and sintered at temperature of 850C under vacuum experienced a electrical condition of 15.7% IACS and microhardness of 196.2 HV which was the best conditions to produce Cu5Ta. Manuscript profile

Open Access Article

15 - Investigation of hydrogen desorption temperature of MgH2-10wt% (Ti, Mn, V and Fe) nanocomposite produced by mechanical alloying
حسین محمدی سید جمال حسینی پور محمد رجبی

Magnesium hydride is one of the attractive hydrogen storage materials because of its hydrogen storage capacity (7.6 wt %), low cost and light weight. However, high hydrogen desorption temperature and a high reactivity toward oxygen limit the use of MgH2 in practical app More

Magnesium hydride is one of the attractive hydrogen storage materials because of its hydrogen storage capacity (7.6 wt %), low cost and light weight. However, high hydrogen desorption temperature and a high reactivity toward oxygen limit the use of MgH2 in practical applications. Many efforts have focused on Mg-based hydrides in recent years to reduce the desorption temperature. These can be accomplished to some extent by changing the microstructure of the hydride by mechanical alloying and also by using proper catalysts. In this work, Ti, Mn, V and Fe elements were added to MgH2 either in the form of powder mixture or prealloyed powder and after 30 h mechanical alloying, the properties of obtained nanocomposites were investigated by X-ray diffractometery, scanning electron microscopy and thermal analysis.  The results showed that the addition of prealloyed powder to MgH2 and 30 h mechanical alloying of powder mixture is more effective in dehydrogenation properties. Manuscript profile

Open Access Article

16 - Effect of Powder Morphology on Thermal properties and strentgh of High Heat Flux Porous Coatings Synthesized by Powder Metallurgy
علی کفلو مونا معیری

Recently, with decreasing energy resources, it is favorable to use new materials to increase efficiency. High heat flux coating is one of the porous coatings that are created on base plate with pressure less sintering of powders. These coatings increase surface, besides More

Recently, with decreasing energy resources, it is favorable to use new materials to increase efficiency. High heat flux coating is one of the porous coatings that are created on base plate with pressure less sintering of powders. These coatings increase surface, besides increasing bubble nucleation sites and permeability. Porosity volume, deboning strength and permeability are the most important physical property of these coatings that affected by powder size and powder morphology as well as sintering conditions. In this research, the effect of powder morphology on physical properties (porosity, deboning strength and permeability) of High Heat Flux porous coatings was investigated. Spherical, dendritic and irregular powders by using a polymeric binder were created on Cu base plate in an atmospheric control furnace (H2-N2) with specified heat treatment cycle (without any pressure). Porosimetery test was carried on porous coating samples. Results for spherical, dendritic and irregular powders were 24.5, 49.5 and 58% respectively. For mentioned samples, deboning strength was, 1.4, 0.52 and 0.82 (kN). Permeability of samples was in 3.3×10-12 to 4.8×10-12 (m2) range. Results show that maximum permeability and porosity were belonged to the irregular powder with minimum strength and spherical powder with maximum strength has minimum permeability and porosity. Manuscript profile

Open Access Article

17 - Study and investigation on the formation of NbAl3-based nanocomposite reinforced by Al2O3 particles: microstructural and thermal analysis investigation
Hossein Mostaan Mahdi Rafiei Mohammad Hasan Abbasi Fathollah Karimzadeh

The aim of this research is fabrication of NbAl3-based nanocomposite via mechanical alloying in order to increase its toughness and high-temperature strength. For this purpose, mixtures of 49 wt.% of aluminum and 51 wt.% of niobium oxides were mixed and mechanically all More

The aim of this research is fabrication of NbAl3-based nanocomposite via mechanical alloying in order to increase its toughness and high-temperature strength. For this purpose, mixtures of 49 wt.% of aluminum and 51 wt.% of niobium oxides were mixed and mechanically alloyed. Phase evolutions, microstructure and morphology of powder particles during milling were studied using X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In order to study the thermal behavior of powder particles, annealing treatment and differential thermal analysis (DTA) were carried out. It was found that the reaction between aluminum and niobium oxide is explosive and during this reaction NbAl3-based nanocomposite reinforced by Al2O3 particle is formed. The as-blended powders were studied by DTA and the results showed that in this condition NbAl3/Al2O3 composite is formed within two stages. At the first step, Nb2O5 is reduced by aluminum. At the second step, the retained aluminum is reacted by niobium and finally NbAl3/Al2O3 composite is formed. Observations by TEM revealed formation of nanostructure and nano-sized reinforcement particles. Manuscript profile

Open Access Article

18 - Synthesis of nanostructured bornite by mechanical alloying and investigate the effect of co-doping Zn and Co on its thermoelectric properties
Ahmad Ostovari Moghaddam Ali Shokuhfar

To improve current solid state thermoelectric devices, high performance materials based on safe and abundant elements is required. Here, the thermoelectric properties of Cu5-2xZnxCoxFeS4 (0 ≤ x ≤ 0.06) nanostructured samples were investigated. First, Cu5-2xZnxCoxF More

To improve current solid state thermoelectric devices, high performance materials based on safe and abundant elements is required. Here, the thermoelectric properties of Cu5-2xZnxCoxFeS4 (0 ≤ x ≤ 0.06) nanostructured samples were investigated. First, Cu5-2xZnxCoxFeS4 nanoparticles were synthesized by high energy ball milling and then consolidated into pellets by hot pressing. X-ray diffraction (XRD) analysis was employed for structural study, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for microstructural analysis, and the thermoelectric properties were evaluated by electrical conductivity and thermal conductivity measurements. XRD data revealed that the crystal structure of the materials to be consistent with a pure bornite phase up to x = 0.04 for Cu5-2xZnxCoxFeS4. The power factor of un-substituted sample was 0.25 mWm-1K-2 which decrease after Co and Zn substitution. Concurrent substituting of Co and Zn for Cu in the range of 0.02 ≤ x ≤ 0.04 changed the p-type conduction of bornite to n-type at room temperature and up to 527 K. Extremely low thermal conductivities of k < 0.30 Wm-1K-1 were obtained for all double substituted samples as a results of the significant mass and strain field fluctuations and the nanostructured nature of the samples. The highest ZT value of 0.35 was attained for x = 0.06. Manuscript profile

Open Access Article

19 - Mechanical alloying and fabrication of Zn-4Mn fragments produced by SPS method for using in short-term implants
Nahid Hassanzadeh Nemati mohammad babaiee erfan chizari davood malekpajouh

Zn-based alloys (Zn) with control of the production process have the potential to give rise to a wide range of properties required for use in short-term implants. For this purpose, in the present study, a Zn-4wt%Mn alloy was prepared by mechanical alloying in three time More

Zn-based alloys (Zn) with control of the production process have the potential to give rise to a wide range of properties required for use in short-term implants. For this purpose, in the present study, a Zn-4wt%Mn alloy was prepared by mechanical alloying in three times of 10, 20 and 30 hours. Then some blocks were made by Spark plasma sintering (SPS) process. Heat treatment of manufactured parts was performed at three temperatures of 150, 200 and 250 ° C. The samples were characterized using XRD, dynamic polarization corrosion test and MTT cell viability evaluation. Also, the surface morphology of the samples was determined using scanning electron microscopy (SEM). The results showed that increasing the milling time to 30 hours created a more homogeneous composition, and the heat treated sample at 250 ° C had the highest corrosion resistance. Cell viability of the heat treated samples at this temperature showed higher viability than other samples. The results of this study are expected to be used in short-term implants. Manuscript profile

Open Access Article

20 - سنتز آلیاژ تیتانیوم (Ti-6Al-4V)به روش آلیاژسازی مکانیکی و بررسی رفتار مکانیکی و زیست فعالی نانوکامپوزیت (Ti-6Al-4V/HA-Clay)
محمدعلی مطلبی ابراهیم کرمیان مجید کریمیان

  ایمپلنت‌های تیتانیمی به علت سبکی و مقاومت در مقابل خوردگی در محیط‌های بیولوژیکی و همچنین دانسیته نزدیک به استخوان بدن، کاربردهای پزشکی خاصی دارند. یکی از آلیاژهای تیتانیم در این زمینه Ti-6Al-4V است، که روش آلیاژسازی مکانیکی به علت نقطه ذوب و شرایط سخت ریخته‌گری ا More

  ایمپلنت‌های تیتانیمی به علت سبکی و مقاومت در مقابل خوردگی در محیط‌های بیولوژیکی و همچنین دانسیته نزدیک به استخوان بدن، کاربردهای پزشکی خاصی دارند. یکی از آلیاژهای تیتانیم در این زمینه Ti-6Al-4V است، که روش آلیاژسازی مکانیکی به علت نقطه ذوب و شرایط سخت ریخته‌گری این آلیاژها روش تولید متداول‌تری است. هیدروکسی آپاتیت به دلیل زیست سازگاری و زیست فعالی بالا، ترکیبی مشابه با ترکیب استخوان درترمیم استخوان بسیار مورد توجه قرار گرفته است. همچنین کلی به علت حضور یون Si که می‌تواند به عنوان جوانه‌زنی در آپاتیت سازی (استخوان‌سازی) عمل کند مورد توجه است. هدف از این پژوهش بررسی زمان و شرایط آسیاکاری جهت آلیاژسازی؛ همچنین بررسی اثرات زمان، دما و شرایط زینترینگ در مرحله متالورژی پودر (PM) بوده است که تأثیر آن‌ها بر روی خواص مکانیکی و رفتار زیست بررسی می‌گردد. در این پژوهش، ابتدا از استخوان گاو، هیدروکسی آپاتیت طبیعی به دست آمده، سپس با استفاده از نانو پودر کلی و روش آسیا کاری پر انرژی نانو کامپوزیت کلی- هیدروکسی تبدیل گردید. در نهایت نمونه‌های بالک آلیاژ تیتانیم محتوی 0%، 10%، 20% و 30% درصد وزنی مخلوط سرامیکی هیدروکسی آپاتیت-کلی تهیه گردید. جهت بررسی خواص مکانیکی، آزمون اندازه‌گیری استحکام فشاری سرد و همچنین ارزیابی زیست فعالی، آزمون زیست فعالی بر روی نمونه‌های متراکم شده انجام گرفت. بررسی نتایج نشان می‌دهد که بهترین خواص مکانیکی و رفتار زیست فعالی در نمونه کامپوزیتی تیتانیمی محتوی 20% وزنی مخلوط نانو کامپوزیت سرامیکی مشاهده گردید؛ بنابراین این نانوکامپوزیت تیتانیمی می‌تواند به عنوان یک کاندیدای مناسب جهت مقاصد مهندسی پزشکی معرفی می‌گردد. Manuscript profile

Open Access Article

21 - ساخت و مشخصه یابی ایمپلنت های نانوکامپوزیتی منیزیمی AZ31/HA-Zeolite به روش آلیاژ سازی مکانیکی و متالورژی پودر
حسن قیصری ابراهیم کرمیان محمد براتی سده

قطعات منیزیمی (مانند آلیاژ AZ31) به علت مقاوم بودن به خوردگی در محیط‌های بیولوژیکی و همچنین دانسیته نزدیک به استخوان بدن کاربردهای پزشکی خاصی دارند. یکی از روش های تهیه آلیاژ، روش آلیاژ سازی مکانیکی است که به علت شرایط حاد ریخته گری این آلیاژ روش تولید متداولتری می باشد More

قطعات منیزیمی (مانند آلیاژ AZ31) به علت مقاوم بودن به خوردگی در محیط‌های بیولوژیکی و همچنین دانسیته نزدیک به استخوان بدن کاربردهای پزشکی خاصی دارند. یکی از روش های تهیه آلیاژ، روش آلیاژ سازی مکانیکی است که به علت شرایط حاد ریخته گری این آلیاژ روش تولید متداولتری می باشد. روش متالورژی پودر (PM) یکی از روش های مطلوب در جهت تولید قطعات منیزیمی بوده که از جمله مجهولات ، زمان و دمای زینترینگ درمی‌باشد. هیدروکسی آپاتیت به دلیل زیست‌سازگاری و زیست-فعالی بالا، ترکیبی مشابه با ترکیب استخوان و امکان رشد ابتدا هیدروکسی آپاتیت طبیعی( گرفته شده از استخوان گاو) توسط روش حالت جامد آسیا کاری پر انرژی HEBM و پودرزئولیت به نانو پودرکامپوزیتی هیدروکسی آپاتیت- پودرزئولیتHZ ( با نسبت وزنی 80 به 20 ) تبدیل گردید. سپس نمونه های بالک آلیاژ منیزیم AZ31 محتوی 0%، 10 % ، 20% و 30% وزنی کامپوزیت سرامیکی HZ به روش متالورژی پودر متراکم سازی و زینترینگ حرارتی گردد. جهت بررسی رفتار مکانیکی، آزمون اندازه گیری استحکام فشاری سرد CCS، سختی و همچنین بررسی سطح مقطع شکست بر روی نمونه های متراکم شده انجام گرفت. از طرفی جهت بررسی ساختار فازی (XRD)، بررسی ریزساختار و سطح مقطع شکست از میکروسکوپ الکترونی روبشی (SEM) انجام گرفت. بررسی نتایح نشان می‌دهد که بهترین خواص مکانیکی در نمونه کامپوزیتی منیزیمی محتوی20% وزنی کامپوزیت سرامیکی(AZ31/HZ20) مشاهده گردید. بنابراین این کامپوزیت منیزیمی می تواند به عنوان یک کاندیدای مناسب با خواص مکانیکی مطلوب در کاربرد های ارتوپدی معرفی می گردد. Manuscript profile

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