اثر دما و زمان عملیات آنیل بر رفتار مغناطیسی نوارهای آلیاژی Nd-Fe-B آماده‌ شده به روش ذوب‌ریسی

نوع مقاله : علمی و پژوهشی

نویسندگان

قادر احمدپور ¹

فرزاد نصیرپوری ²

¹ استادیار گروه مهندسی مواد و متالورژی دانشگاه صنعتی بیرجند.

² گروه مهندسی مواد و متالورژی دانشگاه صنعتی سهند تبریز.

10.22067/jmme.2026.97524.1242

چکیده

در این پژوهش، تأثیر دما و زمان آنیل بر خواص مغناطیسی، ریزساختار و ترکیب فازی نوارهای آلیاژی Nd-Fe- B تولیدشده به روش ذوب‌ریسی بررسی شد. برای این منظور، آزمون‌های پراش پرتو ایکس (XRD)، میکروسکوپ الکترونی روبشی گسیل میدانی (FE-SEM)، طیف‌سنجی پراکندگی انرژی (EDS)، نقشه‌برداری عنصری و مغناطومتر نمونه ارتعاشی (VSM) بر روی نمونه‌ها در سه دمای مختلف (550، 650 و 700 درجه سانتی‌گراد) و در زمان‌های 30، 60 و 90 دقیقه انجام شد. نتایج XRD نشان داد که نمونه بدون آنیل عمدتاً دارای ساختار بی‌شکل است. با آنیل در 650 درجه سانتی‌گراد، فاز سخت Nd₂Fe₁₄B با ساختار نانوبلوری شکل گرفت. در 700 درجه سانتی‌گراد، علاوه بر فاز مذکور، فازهای ثانویه α-Fe و NdFe₄B₄ نیز ظاهر شدند. تصاویر FE-SEM رشد تدریجی دانه‌ها با افزایش دما و زمان را تأیید کرد. توزیع یکنواخت عناصر در دمای 650 درجه سانتی‌گراد توسط EDS و نقشه‌برداری عنصری تأیید شد. بررسی حلقه‌های هیسترزیس نشان داد که بیشترین نیروی وادارندگی (Oe 38/8710Hc =) و نسبت مربعی (781/0Mr/Ms =) مربوط به نمونه آنیل‌شده در دمای 650 درجه به مدت 90 دقیقه حاصل شده است. نتایج نشان داد که در این شرایط، ترکیبی از ساختار نانوبلوری پایدار، قفل‌شدگی مؤثر دیواره‌های حوزه و جفت‌شدگی تبادلی مناسب، به بهینه‌ترین خواص مغناطیسی منجر می‌شود. در مقابل، در دمای 700 درجه، با رشد دانه‌ها و افزایش فازهای نرم، خواص مغناطیسی کاهش یافت. به‌طور کلی، دمای 650 درجه به مدت 90 دقیقه به‌عنوان شرایط بهینه برای دستیابی به خواص مغناطیسی مطلوب و حفظ ساختار نانوبلوری تعیین شد.

کلیدواژه‌ها

آلیاژ Nd-Fe-B

نوارهای ذوب‌ریسی‌شده

عملیات آنیل

فاز Nd₂Fe₁₄B

ریزساختار

خواص مغناطیسی

موضوعات

• مواد پیشرفته

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عنوان مقاله English

Effect of Annealing Temperature and Time on The Magnetic Behavior of Nd-Fe-B Alloy Ribbons Produced by Melt Spinning Method

نویسندگان English

Ghader Ahmadpour ¹

Farzad Nasirpouri ²

¹ Materials Engineering, Faculty of Mechanical and Metallurgical Materials Engineering, Birjand University of Technology, Birjand

² Materials and Metallurgy Faculty , Sahand University of Technology, Tabriz

چکیده English

In this research, the effects of annealing temperature and time on the magnetic properties, microstructure, and phase composition of Nd Fe B alloy ribbons produced by the melt spinning method were investigated. X ray diffraction (XRD), field emission scanning electron microscopy (FE SEM) coupled with energy dispersive spectroscopy (EDS) and elemental mapping, as well as vibrating sample magnetometry (VSM), were employed on samples annealed at three different temperatures (550, 650, and 700 °C) for 30, 60, and 90 minutes. XRD results indicated that the as cast (non annealed) sample exhibited a predominantly amorphous structure. Upon annealing at 650 °C, the hard magnetic phase Nd₂Fe₁₄B was formed. At 700 °C, secondary phases such as α Fe and NdFe₄B₄ also appeared in addition to the main phase. FE SEM micrographs confirmed the gradual grain growth with increasing temperature and time. EDS analysis and elemental mapping verified a uniform elemental distribution at 650 °C. Analysis of hysteresis loops revealed that the sample annealed at 650 °C for 90 minutes exhibited the highest coercivity (Hc = 8710 Oe) and squareness ratio (Mr/Ms = 0.781). These results indicate that, under these conditions, a stable nanocrystalline structure, effective domain wall pinning, and appropriate exchange coupling collectively yield the most favorable magnetic properties. Conversely, at 700 °C, magnetic properties deteriorated due to grain coarsening and the presence of soft magnetic phases. In general, annealing at 650 °C for 90 minutes was identified as the optimum condition for achieving desirable magnetic properties while preserving the nanocrystalline structure.

کلیدواژه‌ها English

Nd-Fe-B alloy

melt-spun ribbons

annealing treatment

Nd₂Fe₁₄B phase

microstructure

magnetic properties

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