The effect of crystallizing procedure on microstructure and characteristics of sputter-deposited TiNi shape memory thin films

Abstract

Two kinds of Ti-rich TiNi shape memory thin films were deposited onto monocrystal silicon substrates at room temperature and high temperature by using the magnetron-sputtering technique. Their crystallizing procedures are different from each other. The first type of film was originally amorphous and post-crystallized at a higher annealing temperature (600 • C) after sputtering, but the second film type was crystallized in situ during sputtering at about 500 • C. It was found that there are clear differences of microstructure and characteristics between both kinds of film, such as grain size, growth texture, stress range, phase transformation behaviors etc. In order to improve and enhance film properties, the objective of the present work is to reveal the reason for these differences occurring and understand the relationship between the crystallizing procedures, microstructures and characteristics of the films.

Effect of Pd content on crystallization and shape memory properties of Ti–Ni–Pd thin films

“…The smaller grain size in the thin film crystallized in situ was also confirmed in Ti-Ni binary alloy [37]. It is considered that the difference of grain size between two specimens is due to the different crystallization processes.…”

Micromachined Shape-Memory-Alloy Microactuators and Their Application in Biomedical Devices

“…The temperature range for the composition in [44] increased slightly to around 13-27 °C, compared to the composition in [50]. The same is true for the compositions in [51,52]. Besides the transformation temperature, another important feature of SMA is the SME, which can be described as the ability of the material to recover its original shape.…”

Ni-Ti Akıllı Alaşım İnce Filmin Sıcaklığa Bağlı X-Ray Kırınımı ile Karakterizasyonu ve Faz Dönüşümü Tespiti

“…Başka bir çalışmada ise ikili depolama tekniği ile depolanan farklı kalınlıklardaki filmler XRD ile analiz edilmiş ve oda sıcaklığında yapılan analizlerde 36 ve 42 aralığında martenzit pikler tespit edilmiştir [8]. Bir diğer çalışmada, farklı sıcaklıklarda tavlanmış titanyumca zengin NiTi ince filmler oda sıcaklığında X-ışınımı ile karakterize edilmiş, oda sıcaklığında yapılan analizlerde numunelerden birinin austenit diğerinin ise martensit olduğu gözlenmiştir [9]. Amorf yapının aksine depolama sonrası kristal yapının son derece önemli olduğu bu alaşımlarda farklı sıcaklıklarda gerçekleştirilen tavlama işleminin etkileri de araştırmacılar tarafından XRD ile incelenmiş, tabakalı olarak depolanan ince filmlerde tavlama işlemi etkisi kristal yapıları XRD ile incelenerek incelenmiştir [10,11].…”