Tatsuya Matsue

Residual stress and its thermal relaxation in TiN films

Abstract The structure and residual stresses of TiN coated films were investigated by X-ray diffraction. TiN films were deposited onto substrates of spring steel by a multi-are method at different deposition temperatures. The TiN films, approximately 4 μm in thickness, exhibited high {111} orientation. The residual stresses in the TiN films were evaluated by the two-exposure method to obtain the lattice strains for 222 diffraction at ψ=0° and 70.5° with Cu Kα radiation. The results revealed very high compressive residual stresses of about −5.8 to −3.5 GPa which are one order larger than the thermal residual stress expected from the thermal strain mismatch between the film and the substrate. These residual stresses in the TiN films decreased on increasing the annealing temperature, and decreased finally to the level of the thermal residual stress after annealing at temperatures above 1073 K.

Residual stress in TiN film deposited by arc ion plating

Abstract TiN films were deposited on aluminum and stainless steel substrates by arc ion plating (AIP). Bias voltages, nitrogen gas pressures and arc currents were changed to examine their role on the hardness and residual stress of a TiN film. Vickers microhardness tests revealed high hardness value (HV = 2250–2500) which depends on both nitrogen gas pressures and arc currents. From the X-ray diffraction pattern, it was found that the crystal orientation of the TiN film markedly varied with the bias voltage. Residual stresses in the TiN film were measured by the two-exposure X-ray stress analysis as a function of the nitrogen gas pressure, arc current. Very high compressive residual stresses, −5 GPa in the films on aluminum substrates and −7 GPa in the film on a stainless steel substrate, were observed.

Thermal relaxation of residual stresses in TiN films deposited by arc ion plating

Abstract The present study investigates crystal orientations and residual stresses in TiN films deposited by arc ion plating. TiN films approximately 2.0 μm thick were deposited on a steel substrate. With a bias voltage of 0 V, the TiN film exhibited strong {110} texture, whereas the dominant orientation of the film deposited at −100V was {111}. TiN films had very high compressive residual stresses: −8.6 GPa in the {110} textured film and −10.0 GPa in the {111} textured film. These residual stresses decreased with increasing annealing temperature and the reduction rate was greater for the {111} than for the {100} film. The behavior of residual stresses in the {111} and {110} textured layers of {111}/{110} textured double-layer film was identical to that for single-layer films.

In situ stress measurement of fiber reinforced composite in low temperature state by neutron diffraction

The tungsten fiber reinforced titanium composite (W/Ti) was produced by the spot welding method. The internal stress alteration of the W/Ti composite was measured by the neutron diffractometer, DN1, which had been installed at beam port #6 in National Nuclear Energy Agency Indonesia. The two-dimensional detector and cryostat system were mounted on the DN1 diffractometer, and the residual stress alterations were measured by the in situ neutron stress measurement technique under the cooling cycles from 300 K to 10 K. Residual stresses in tungsten fiber were investigated at several temperatures. In the longitudinal fiber direction, the thermal residual stresses of tungsten fiber became a large compressive state and represented the maximum value is about -950 MPa. The calculated results of the simple elastic model agreed with the experimental results of the in situ thermal stress measurement qualitatively. It is assumed that the stresses in the fiber longitudinal direction are the dominant stresses in the W/T...

Residual Stresses of Cr-N Films Deposited by Arc Ion Plating Investigated Using Synchrotron Radiation

The structures of Cr-N films deposited by arc ion plating on steel substrates were investigated using a synchrotron radiation system that emits ultraintense X-rays. The Cr-N films were found to be mainly composed of {110} oriented CrN crystals, but they also had a small component of randomly oriented Cr2N crystals. The CrN220 diffraction shifts to a high diffraction angle as the annealing temperature increases. In contrast, the peak position of the Cr2N211 diffraction hardly changes with an increase in the annealing temperature up to 873 K. The ratio of nitrogen and oxygen to chromium at the film surface and inside in the film was estimated by Auger electron spectroscopy. After annealing at 973 K, the surface layer was oxidized, but the composition inside the Cr-N films (N/Cr = 0.83) remained unchanged. The residual stress in a 1600-nm-thick as-deposited CrN layer was found to be -11.0 GPa. The residual stresses of Cr-N films relaxed to thermal stress levels on annealing. However, the residual stress in the Cr2N layer could not be evaluated.

Stress Estimation of Titanium Casting Alloy by X-ray Measurement Technique of Single Crystal

Residual stresses in titanium casting alloy were estimated by X-ray stress measurement technique. There are two problems in the condition of X-ray stress measurement. Firstly, the titanium casting alloy has the large crystal grains. These coarse grains were generated under solidification processes and those sizes are approximately 2 millimeter in this study. These coarse crystal grains interfere with an accurate stress measurement due to the unstable diffraction profile [1]. This is because the existence of a sufficient number of isotropic crystal grains in the X-ray irradiation area are based on the X-ray diffraction theory. In this study, the stress measurement technique of single crystal materials was adopted for the solution of this fundamental problem [2, 3]. Because the coarse crystal grain was treated as a single crystal, the high intensity diffraction profiles were observed from a certain direction with investigations of crystal orientation. The problem with the coarse crystal grain in titanium casting alloy were cleaned up by the employment of the single crystal measurement technique. Secondly, the results from this study show that the position of crystal grain within the X-ray irradiation area greatly influenced the residual stress values. Therefore, in the present paper the erasing method of this position effect was tried and discussed [4]. Finally, the improvement of the accuracy of this method for the residual stress measurement in titanium casting alloy under the several bending stresses was confirmed. These results show that the erasing method in this study is an effective correction method.

Residual Stress Measurement in Sputtered Copper Thin Films by Synchrotron Radiation and Ordinary X-Rays

Residual stresses in nano-size copper thin films could be investigated by using synchrotron radiation (SR) because the brightness and parallelism of synchrotron radiation beam are higher than the ordinary characteristic X-rays. The copper thin films were deposited on quartz by dc planer magnetron sputtering under the conditions of two different substrate temperatures. In the case of 743 to 770K, the thicknesses of copper films changed from 15 to 960nm. Crystal orientation and residual stress in the films were measured by using SR and characteristic X-rays as a function of substrate temperature and film thickness. In addition, we observed the film surfaces with a scanning electron microscope (SEM) and atomic force microscope (AFM). The following results were obtained: (1) copper films were formed in three processes; a tiny granular structure, a growing island structure and a uniform film structure, (2) sputtered copper films were {111}-oriented except for the thinner film below 160nm at the deposition temperature of 713-750 K and below 30nm at 743-770 K, (3) tensile residual stresses were developed in all films, and (4) different residual stress relaxation occurs depending on a film structure.

Thermal Stress Behavior of Aluminum Nanofilms under Heat Cycling

In‐situ thermal stress in aluminum nanofilms with silicon oxide glass (SOG) passivation was investigated by using synchrotron radiation at the SPring‐8. Aluminum films of varying thickness (10, 20, 50 nm) were deposited on thermally oxidized silicon wafers by RF magnetron sputtering. Each specimen was heated in air over two cycles between room temperature and 300°C. The following results were obtained: (1) {111} planes of aluminum nanofilm crystals were oriented parallel to the substrate normal; (2) the intensity of 111 diffraction was almost independent of temperature except in the case of the 50‐nm‐thick film; (3) the FWHM of 111 diffraction was almost independent of temperature at any given film thickness; and (4) for all films, the thermal stress varied linearly with heating temperature, and the hysteresis between the heating and cooling steps disappeared.

Crystal orientation and residual stress in TiN film by synchrotron radiation

Abstract The residual stress in a TiN film, the thickness of which is less than 1 mm, deposited by arc ion plating was measured using the SPring-8 synchrotron radiation facility installed at Japan Synchrotron Radiation Research Institute (JASRI). Films thicker than 300 nm have a {111} texture, whereas those with a thickness of 100 nm have a relatively random orientation. Instead of the conventional laboratory X-ray equipment, ultrabright synchrotron radiation can be used to precisely measure the residual stress in thin films with a thickness of 100 to 800 nm. The residual stress in thicker TiN films is about 7 GPa in compression and it is not affected by the film thickness. The slightly small compressive stress in a film of 100 nm in thickness may be due to the different crystal orientations in the film.

Effects of Depositing Temperature and Film Thickness on Residual Stress of TiN Coated Materials.

Large residual stress is formed in the coating of ceramic material deposited on a metal substrate because of difference in thermal expansion coefficient between the film and the substrate and of some other reasons. The residual stress greatly influences the mechanical properties of the film and the coated material. Therefore, the residual stress is one of the most important factors on evaluating the strength of coated materials.In the present investigation, we studied the residual stress in TiN film deposited on a substrate of spring steel by a multi-arc method as a function of depositing temperature and film thickness. The residual stress in the substrate layer near the interface was also investigated.The TiN film exhibited highly {111}-orientation, i.e., [111] of TiN crystals orients parallel to the surface normal of the substrate within ±10 degrees. The residual stress in the TiN film could be evaluated by the two-exposure method with getting the lattice strains for 222 diffraction at φ=0° and 70.5° determined by the relation of crystallographic orientation. The results revealed the compressive residual stress of -5.5--3.5GPa which is very large compared with the thermal residual stress due to the thermal strain mismatch between the film and the substrate. The residual stress value was greatly depended on the depositing temperature; it decreased with increasing temperature, and thickness of TiN film and increased with increasing film thickness. The residual stress in the substrate was compressive and below -30MPa probably due to the implantation of Ti ions into a shallow layer of the substrate.