【作者】 曹伟产；

【导师】 卢正欣；

【作者基本信息】 西安理工大学 ， 材料物理与化学， 2007， 硕士

【摘要】 本文以TiNi形状记忆合金板作为靶材,利用磁控溅射法制备了近等原子比的TiNi合金薄膜,通过衬底加热和晶化退火两种方法获得晶化薄膜,利用TEM、SEM、XRD、DSC等测试方法,系统分析了退火温度、衬底加热温度及Ti含量等对薄膜组织结构和相变过程的影响。研究结果表明:室温下,磁控溅射方法制备的TiNi合金薄膜为非晶态,薄膜以柱状生长。随溅射功率的增大和Ti含量的增加,薄膜的晶化温度下降;富Ni薄膜在晶化退火的过程中伴随有析出相产生,晶化过程为:非晶→非晶+B2+Ti₃Ni₄→B2+Ti₃Ni₄。非晶富Ni薄膜经520℃晶化退火后,可获得B2相等轴晶,晶粒大小在50nm左右。随退火温度升高,薄膜中的B2相和Ti3Ni4相的晶粒也随之长大,在560℃时B2相晶粒在500nm左右。随退火温度的升高Ti3Ni4相形貌变化规律为:细小颗粒→细小椭圆片状→椭圆透镜片状→粗片状。衬底加热480℃以上获得的富Ni薄膜为晶态,晶粒大小比较均匀,薄膜的生长过程属于层核生长型。随薄膜厚度增加,B2相晶粒由等轴晶转变为柱状,距离基片越远这种生长形式愈加明显。衬底加热可以降低薄膜的晶化温度,同时可以有效的抑制析出相的产生。富Ni薄膜在降温过程中发生两步相变,其顺序为A→R、R→M相变;在升温过程发生只有一步相变,即M→B2的转变。富Ti薄膜在530℃晶化退火后,室温下薄膜中存在三种相,B2相基体、Ti2Ni相和Ti₃Ni₄相,衬底530℃加热溅射富Ni薄膜在室温下组织中只存在B2相。两种工艺获得的晶化薄膜相变行为与富Ni薄膜一致。由于第二相Ti₂Ni的出现,富Ti薄膜与富Ni薄膜相比相变温度明显提高。薄膜在升、降温过程中Ti₂Ni相不发生变化。在不同溅射条件下制得的TiNi薄膜在奥氏体状态下的残余应力均为拉应力,在溅射功率和工作气压相同的情况下,退火温度越高,残余应力越小。溅射时间延长,薄膜厚度增加,应力减小。衬底温度越高残余应力越大,而且明显高于真空退火薄膜的应力值。更多还原

【Abstract】 In this paper, the near atomic ratio TiNi alloy films were deposited by magnetron sputtering using TiNi shape memory alloy sheet material as target. Crystallized TiNi films were obtained through vacuum annealing or heating substrate. Then, the influence of annealing temperatures, substrate temperature and the content of Ti on the microstructure and phase transformation of the films were discussed systematically by TEM、SEM、XRD、DSC.,respectively.Through the analysis, the experimental results were as follows:The films,which growed as prismatic were amorphous when the TiNi films were prepared by magnetron sputtering process at room temperature. The content of Ti and the sputtering power can change the crystallization temperature of TiNi amorphous films. As the increasing of the content of Ti and the sputtering power, the crystallization temperature could be decreased. Precipitated phase was formed in the annealing process of the films riched Ni, the process of crystallization can be described as follows, amorphous→amorphous+B2+Ti₃Ni₄→B2+Ti₃Ni₄. B2 equiaxed grains were obtained after the amorphous films riched Ni annealed at 520℃, and the grain size was about 50nm. As the increasing of annealing temperature, the grains of Ti3Ni4 and B2 growed, and the grain size of B2 was about 500nm at 560℃. As the increasing of annealing temperature, the change process of Ti₃Ni₄ morphology can be described as follows, small grain→small elliptical flake→elliptical lens flake→big flake.The films riched Ni, with uniform grain size, obtained by heating substrate to 480℃was crystal, and the films growed in the mode of two-dimensional layer and three-dimensional island alternatively. As the increasing of thickness of the film, B2 phase changed from equiaxed grain to prismatic, and the farther the distance to substrate was the more obvious this growth model. Crystallization temperature of the films could be decreased through heating substrate, and the formation of precipitated phase could also be depressed effectively.A→R and R→M phase transformation of the films riched Ni occurred at the temperature dropping, but only M→B2 phase transformation occurred at the process of heating-up.The films contained three different phase, B2、Ti2Ni and Ti3Ni4 phase, after TiNi films riched Ti were annealed at 530℃. Only B2 phase existed in TiNi films riched Ni through heating substrate to 530℃. Phase transformation behavior of crystallized films obtained by these two process is consistent with TiNi films riched Ni. Phase transformation temperature of the films riched Ti increased obviously comparing with the films riched Ni because of appearance of second phase Ti₂Ni. Residual stress of austenitic TiNi film obtained at different sputter conditions is tensionstress. When the sputtering power、argon gas pressure were all the same, the higher annealing temperature was, the smaller residual stress is; As the increasing of the sputter time, thickness of the film increased and the residual stress decreased. The higher substrate temperature is, the larger residual stress is, and it is obviously larger than the vacuum annealing films.更多还原