نویسندگان
کرج، مشکین دشت، پژوهشگاه مواد و انرژی
چکیده
سیلیساید تیتانیم (Ti5Si3) بدلیل داشتن خواص ویژه مطلوب بعنوان یکی از مواد مورد توجه برای کاربرد های سازه ای دما بالا شناخته می شود. در این پژوهش نانو آلیاژها و کامپوزیت های برپایه Ti5Si3 به روش سنتز خود احتراقی دما بالای فعال شده مکانیکی تولید شد. برای این منظور پودرهای Ti، Si و Al بر طبق استوکیومتری های Ti62.5Si37.5 ، Ti62.5Si30Al7.5 و Ti62.5Si22.5Al15 توزین و توسط آسیاب سیاره ای پر انرژی مخلوط شدند. نمونه برداری در زمان های 3 و 6 ساعت انجام پذیرفت. پودر های بدست آمده از آسیاب توسط پرس تک محور فشرده شدند و برای انجام واکنش SHS به کوره تیوبی اتمسفر کنترل فرستاده شدند. نتایج بدست آمده از پراش پرتو ایکس XRD نشانگر سنتز فاز اصلی Ti5Si3 در تمامی نمونههاست. با افزایش مقادیر آلومینیم در کنار فاز اصلی Ti5Si3 فاز جانبی Ti3Al قابل تشخیص می باشد. محاسبه اندازه کریستالیت ها بر اساس روابط مربوط به پهن شدگی پیک ها نشانگر سنتز نمونه هایی در ابعاد نانومتری می باشد که با افزایش Al این امر تشدید می شود. تصاویر بدست آمده توسط میکروسکوپ الکترونی روبشی SEM مجهز به آنالیزگر تفکیک انرژی پرتو ایکس (EDS) نشانگر جایگزینی مقادیر قابل ملاحظه از اتمهای Al در شبکه کریستالی Ti5Si3 و تشکیل محلول جامد Ti5(Si,Al)3 می باشد.
کلیدواژه‌ها
عنوان مقاله [English]
Effect of substitution of Si by Al on the structural and microstructural properties of nano Ti5Si3 based alloys prepared by MASHS
نویسندگان [English]
- Kian Kasraee
- Ali Tayebifard
- Esmaeil Salahi
Material & Energy Research Center (MERC), Karaj, Iran
چکیده [English]
Ti5Si3 has gained significant attention as a high temperature structural material due to its unique combination of properties. In the present work nanostructured Ti5Si3 based alloys and composites were synthesized by using mechanically activated self-propagating high-temperature synthesis (MASHS). For this purpose, Ti, Si and Al were mixed according to nominal compositions of Ti62.5Si37.5, Ti62.5Si30Al7.5 and Ti62.5Si22.5Al15 and milled by high energy ball milling for 3 and 6 h. The milled powders were pressed to form pellets and then green compacts were placed in a tube furnace to synthesize. The samples were characterized by X-ray diffraction (XRD) analytical technique and scanning electron microscope (SEM) equipped with an energy-dispersive spectrum (EDS) analyzer. The results have shown, Ti5Si3 were synthesized in all samples as main phase. Ti3Al is synthesized beside the Ti5Si3 in the Ti62.5Si22.5Al15 composition. Crystallites size of Ti5Si3 which had been synthesized by MASHS process was measured by Williamson-hall method. Results howed the entire MASHS product have crystallites size under 100 nm. The EDS results have shown that significant amount of Si can be replaced by Al in the Ti5Si3 structure.
کلیدواژه‌ها [English]
- Titanium silicide
- SHS
- Mechanical activation
- Nano composite
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