Sinan AKSÖZ, Bülent BOSTAN, YAVUZ KAPLAN

Borlama İşleminin T/M Tekniği ile Üretilmiş NiTi Alaşımının Mikroyapı Ve Mikrosertliğine Etkilerinin İncelenmesi

Bu çalışmada, toz metalürjisi yöntemiyle önalaşımlı NiTi tozlarından numuneler üretilmiştir. Presleme işlemi yaklaşık 300ºC sıcaklığa sahip kalıpta 700MPa basınçta gerçekleştirilmiştir. Preslenen numunelere, yüksek saflıktaki Argon atmosferinde ve yüksek sıcaklığa dayanıklı Quartz cam tüp içerisinde, 1200ºC sıcaklıkta ve 120 dakika sürede sinterleme işlemi uygulanmıştır. Sinterlenen numunelere sırasıyla 900ºC ve 1000ºC’de 6 ve 12 saat borlama işlemlerine tabi tutulmuştur. Çalışmada mikroyapı incelemeleri için, FESEM, EDS, MAP, Optik Mikroskop analizleri yapılırken sertlik ölçümleri için mikrosertlik ölçümleri ve görüntüleri alınmıştır. Araştırmada uygulanan tüm borlama parametrelerinde numunelerin yüzey sertlikleri artmıştır. Ayrıca en büyük tabaka kalınlığı ve en yüksek sertlik değeri 1000°C’de 12 saat borlanan NiTi alaşımında sırasıyla yaklaşık 50 µm ve 2074,9 HV olarak ölçülmüştür.

Anahtar Kelimeler:

Önalaşımlı NiTi, Toz Metalürjisi, Borlama, Mikrosertlik, Mikroyapı

An Investigation on the Effects of Boronizing Process on Microstructure and Microhardness of NiTi Alloy Produced by P/M Technique

In this study, samples were produced by the powder metallurgy method from pre-alloyed NiTi powders. The pressing process was carried out at 300ºC temperature under 700MPa pressure. The pressed samples were sintered at 1200ºC for 120 minutes in high temperature resistant Quartz glass tube under a high purity Argon atmosphere. Sintered samples were boronized at 900ºC and 1000ºC for 6 and 12 hours. FESEM, EDS, MAP and Optical Microscope analyzes were carried out for the microstructure analysis. In addition, microhardness measurements and microhardness images were taken for hardness measurements. The surface hardness of the samples increased in all applied boronizing parameters. The largest layer thickness and highest hardness value were obtained at 1000°C for 12 hours as 50 µm and 2074.9 HV respectively.

Keywords:

Pre-Alloyed NiTi, Powder Metallurgy, Boronizing, Microhardness, Microstructure,

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