ANALISIS MIKROSTRUKTUR MATERIAL MAGNETIK BERBASIS Nd-Fe–B DAN Sm–Co UNTUK APPLIKASI MAGNET PERMANEN HIBRID

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Telah dilakukan preparasi, kajian dan pengamatan mikrostruktur sampel magnet hibrid SmCo₅ – Nd₁₂Fe₈₂B₆ setelah melalui proses preparasi teknik metalurgi serbuk. Dengan mensubsitusi unsur Dy ke dalam Nd-Fe-B maka terbentuk ingot paduan fasa  Nd_12-xDy_x Fe₈₂B₆ (at.%) dengan x = 0, 1, 2, 6 dan 9, selanjutnya ingot di mill untuk menghasilkan serbuk halus (Nd,Dy)-Fe-B dengan ukuran partikel 20-40 mm. Serbuk Sm-Co dan (Nd,Dy)-Fe-B dicampur dengan perbandingan 80:20 (wt%). Material tersebut dipadatkan  dalam cetakan kemudian diberi siklus perlakuan panas dan sampel yang sangat padat dihasilkan. Telah dihasilkan mikrostruktur material hibrid (Pr,Nd,Sm,Dy)₂(Fe,Co)₁₄B, (Pr,Nd,Sm,Dy)Co₅ setelah tahapan sinter pada temperatur 1150 ^oC dan anil pada temperatur   850 ^oC selama 5¹/₂ jam dan diikuti pendinginan cepat kedalam air. Juga telah diamati bahwa ”fasa bingkai” mempunyai tipe 1-5 dan 2-14-1 disamping fasa utama 2-14-1 dan 1-5 dalam material hibrid seperti ditunjukkan oleh SEM-EDS, XRF dan XRD. Struktur mikro tersebut sepertinya berpenampilan ”unik” karena berbeda dengan struktur mikro material magnet konvensional yang berbasiskan Nd-Fe-B atau Sm-Co. Kesimpulan dari penelitian ini adalah bahwa hibridisasi dua fasa magnetik permanen yang berbeda telah memberikan informasi baru yaitu telah dihasilkannya struktur mikro yang ”unik” walaupun fasa-fasa magnetik 1-5 dan 2-14-1 masih tetap dipertahankan sebagai fasa-fasa utama dalam material material hibrid.

The preparation, investigation and observation of microstructure of the SmCo₅ – Nd₁₂Fe₈₂B₆ hybride magnetics sample which after preparation processing by powder metallurgy technique have been done. The element of Dy was substituted into Nd-Fe-B to produces Nd_12-x Dy_x Fe₈₂B₆ (at%) alloys with x = 0, 1, 2, 6 and 9. The ingots were further ball milled to produce fine powders of (Nd,Dy)-Fe-B in the size range of  20-40 µm. Both kinds of powders Sm-Co and Nd-Fe-B base were then mixed with ratio 80:20 (wt%). This materials were compacted in a die, then fully dense compacting samples were obtained after the application of designed heat treatments. It was found that microstructure for hybrid materials consisted of (Pr,Nd,Sm,Dy)₂(Fe,Co)₁₄B, (Pr,Nd,Sm,Dy)Co₅ obtained after a sintering step at temperature 1150 ^oC and annealed at a temperature of 850 ^oC for 5¹/₂ hours and followed by quenching into water. It was also observed that a ”frame phase” of 1-5 and 2-14-1 types in addition to the main phase of 2-14-1 and 1-5 in hybride materials as shown by SEM-EDS, XRF and XRD. This kind of microstructure is assumed unique because different with conventional microstructure of sintered Nd-Fe-B or Sm-Co based materials. The conclusion of the current study is that hybridization of two different hard magnetic phases have given new information in that it has produced unique microstructures while the magnetic phases of 1-5 and 2-14-1 still remain as the main phases in hybride materials.

Keyword: Nd-Fe-B, Sm-Co, permanent magnets, sintered magnets, magnetic properties.