Intermetallic compound formation at the Interface of ... E-mail: moh.ammar_mofid@ Intermetallic

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  • Summer 2019, Volume 22, number 2

    135

    Summer 2019, Volume 22, number 2

    84

    Spring 2016, Volume 19, Number 1 METALLURGICAL ENGINEERING The Journal of Iranian Metallurgical and Materials Engineering Society

    http:metalleng.ir/ 4

    Hot deformation of an extruded Mg–10Li–1Zn alloy was studied by compression testing in the temperatures range of 250- 450˚C and strain rates of 0.001–0.1s−1. During hot compressive deformation of the Mg-10Li-1Zn alloy, flow stress curves reach a maximum value and then reach a steady state which is indicative of the occurrence of dynamic recrystallization. Be- cause of the activation of softening mechanisms at higher temperatures and lower strain rates, this phenomenon is more pronounced at lower temperatures and higher strain rate. The flow stress of the Mg–10Li–1Zn alloy at elevated tempera- tures was modeled via an Arrhenius-type constitutive equation. The values for the activation energy of about 103 kJ mol–1 and the power-law stress exponents in the range of 5.2–6.0 obtained from the Arrhenius-type model indicate that the domi- nant mechanism during hot deformation of the Mg–10Li–1Zn alloy is dislocation climb which is controlled by the lattice self-diffusion of Li atoms. Key words: Mg-Li alloys, Hot deformation, Constitutive equations

    A B S T R A C T

    Citation: Shalbafi M, Roumina R, Mahmudi R. The Study of Hot Deformation Behavior of an Mg-10Li-1Zn Alloy by Arrhenius Constitutive Equations. Metallurgical Engineering. 2016; 19(1):4-12. http://dx.doi.org/10.22076/me.2017.27135.1030

    : : http://dx.doi.org/10.22076/me.2017.27135.1030

    * Corresponding Author: Reza Roumina, PhD Address: School of Metallurgy and Materials Engineering, University of Tehran, Tehran, Iran. Tel: +98 (21) 82084097 E-mail: roumina@ut.ac.ir

    Research Paper The Study of Hot Deformation Behavior of an Mg-10Li-1Zn Alloy by Arrhenius Constitutive Equations

    1. MSc., School of Metallurgy and Materials Engineering, University of Tehran, Tehran, Iran. 2. Assistant Professor, School of Metallurgy and Materials Engineering, University of Tehran, Tehran, Iran. 3. Professor, School of Metallurgy and Materials Engineering, University of Tehran, Tehran, Iran.

    Mostafa Shalbafi1, *Reza Roumina2, Reza Mahmudi3

    * Corresponding Author: Sahar Mollazadeh Beidokhti, PhD Address: Department of Materials and Metallurgy engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran. Tel: +98 (51) 38805167 E-mail: mollazadeh.b@um.ac.ir

    Effect of Manufacturing Route on Microstructure and Mechanical Properties of Calcium Phosphate/Gelatin-Starch Composite Scaffold

    Faezeh Darvishian Haghighi1, *Sahar Mollazadeh Beidokhti2, Samaneh Sahebian Saghi3, Zahra Tayarani Najaran4

    1- MSc. Student, Department of Metallurgy and Materials engineering, Faculty of engineering, Ferdowsi University of Mashhad, Mashhad, Iran. 2- Assistant Professor, Department of Materials and Metallurgy engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad,

    Iran. 3- Assistant Professor, Department of Materials and Metallurgy engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad,

    Iran. 4- Associate Professor, Department of Pharmacodynamics and Toxicology, Mashhad University of Medical Sciences, Iran

    Citation: Darvishian Haghighi F, Mollazadeh Beidokhti S, Sahebian Saghi S, Tayarani Najaran z. Effect of Manufacturing Route on Micro- structure and Mechanical Properties of Calcium Phosphate/Gelatin-Starch Composite Scaffold. Metallurgical Engineering 2019: 22 (2): 84-95 http://dx.doi.org/10.22076/me.2019.101173.1228

    doi : http://dx.doi.org/10.22076/me.2019.101173.1228

    A B S T R A C T

    There are plenty of bone damages due to different reasons these days. In order to heal of damaged area, utilizing of the scaffold is necessary. The main aim of this research is fabrication and investigation of Calcium Phosphate/Gelatin-Starch composite scaffolds. After synthesizing the Calcium Phosphate particles via sol gel route, three different methods were used to manufacture Calcium Phosphate/ Gelatin scaffolds. The method which has the porous structure was selected as the main method for fabricating Calcium Phosphate/ Gelatin-Starch scaffolds. Weight percentage ofstarch and applying the Gelatin-Glutaraldehyde coating were chosen as two variations. According to mechanical properties results, the sample with 60 weight percentage of Gelatin and 40 weight percentage of Starch has the highest final flexural strength which are 4.5 and 2.3 MPa for samples with and without Gelatin-Glutaraldehyde coating respectively. The SEM results show the completely porous structure with interconnected pores on the surface of coated samples and some local pores in internal parts of the scaffolds. According to the result of cell culture, these scaffolds provide surfaces that facilitate the response of stem cells related to attachment, survival, and proliferation.

    Keywords: Scaffold, Gelatin, Starch, Calcium Phosphate Particles, flexural Strength.

    Accepted: 24 November 2019Received: 16 February 2019

    * Corresponding Author: Mohammad Ammar Mofid, PhD Address: Department of Petroleum, Mining and Material Engineering, Central Tehran Branch, Islamic Azad University, Tehran, Iran. Tel: +98 (9124220622) E-mail: moh.ammar_mofid@iauctb.ac.ir

    Intermetallic compound formation at the Interface of Diffusion Bond and Friction Stir Weld of Al/Mg joints

    *Mohammad Ammar Mofid1,Hamid Naeimian2

    1- Assistant Professor, Department of Petroleum, Mining and Material Engineering, Central Tehran Branch, Islamic Azad University, Tehran, Iran. 2- MSc. Student, Department of Petroleum, Mining and Material Engineering, Central Tehran Branch, Islamic Azad University, Tehran, Iran.

    Citation: Mofid M.A, Naeimian H. Intermetallic compound formation at the Interface of Diffusion Bond and Friction Stir Weld of Al/Mg joints. Metallurgical Engineering 2019: 22 (2): 135-143 http://dx.doi.org/10.22076/me.2019.107087.1244

    doi : http://dx.doi.org/10.22076/me.2019.107087.1244

    A B S T R A C T

    Dissimilar joining of Al5083 to MgAZ31 was performed through friction stir welding (FSW) and diffusion bonding (DB). A constant tool rotation rate of 400 rpm and travel speed of 50 mm/min was used for FSW. The peak temperature of this speci- men was raised to maximum of 435°C at the advancing side of the FS weld. Thermal cycle of the FSW specimen showed a distinct plateau at about 430 °C, lasting for about 8 s. At the travel speed of 50 mm/min, the distance corresponding to 8 s is about7mm, which is the pin diameter. The presence of the temperature plateau indicates that the temperature at eachthe- rmocouple remained constant as the pin passed it. It further indicates that a eutectic reaction probably occurred, and kept the temperature constant as the pin passed by. The weld had anirregular shaped region in the weld center of DB weld and,having a different microstructure and hardness from the two base materials. The irregular shaped region in DB weld, contained a large volume of intermetallic compound Al12Mg17. The present study suggests that constitutional liquation and solid state diffusion at the interface resulted in the intermetallic compound formation in the weld center.

    Keywords: Friction stir weld, Diffusion bond, Temperature profile, Mg alloy, Interface microstructure.

    Accepted: 4 November 2019Received: 29 April 2019

  • 136

    تابستان 1398 . دوره 22 . شماره 2

    * نویسنده مسئول: دكتر محمدعمار مفید

    نشانی: تهران، دانشگاه آزاد اسالمی واحد تهران مرکزی، دانشکده فنی مهندسی، گروه مهندسی نفت معدن و مواد. تلفن: )9124220622( 98+

    moh.ammar_mofid@iauctb.ac.ir :پست الکترونیکی

    Al/Mg تشکیل ترکیبات بین فلزی در فصل مشترک جوش نفوذی و جوش همزن اصطکاکی اتصال

    *محمدعمار مفید1، حمید نعیمیان2

    1- استادیار، گروه مهندسی نفت معدن و مواد دانشکده فنی مهندسی دانشگاه آزاد اسالمی واحد تهران مرکزی، تهران، ایران. 2- دانشجوی کارشناسی ارشد، دانشکدهفنی و مهندسی، دانشگاه آزاد اسالمی واحد تهران مرکزی، تهران، ایران.

    چکیده

    400 rpm از سرعت چرخش FSW انجام شد. برای نمونه )FSW( به دو روش جوشکاری نفوذی و جوشکاری همزن اصطکاکی AZ 31 اتصال آلیاژ آلومینیوم 5083 و آلیاژ منیزیم و سرعت حرکت خطی mm/min 50 استفاده شد. دمای اندازه گیری شده در این نمونه تا بیشینه C° 435 در اطراف سمت پیشرونده ابزار افزایش یافت. چرخه دمایی نمونه FSW نشانگر یک ترازشدگی در دمای حدود C° 430 بود که در حدود 8 ثانیه ادامه دارد. وجود این ترازشدگی دمایی، مبین آن است که با عبور پین از روی هر دماسنج، دما در آن دماسنج، ثابت باقی می ماند. این موضوع می تواند مبین آن باشد که احتماال یک واکنش یوتکتیک اتفاق افتاده و همین موضوع سبب ثابت ماندن دما در لحظه عبور پین از روی دماسنج شده است. جوشکاری نفوذی در بیشینه دمایی که در هنگام FSW تجربه می شود )C° 435( و مدت زمان