Based on the problem that the ferromagnetic target is difficult to be sputtered normally in magnetron sputtering magnetic thin films, in order to improve the preparation process of the target and improve the magnetic leakage rate of the target surface, combined with the differential scanning calorimetry curve of CO CR TA alloy, the heat treatment of CO CR TA alloy was carried out by different heat treatment systems, and the phase structure and texture of CO CR TA alloy under different heat treatment systems were measured After heat treatment, the main phase of CO CR TA alloy changes from face centered cubic co phase to close packed hexagonal co phase, forming {1210} and {1010} linear texture with c axis tending to parallel rolling surface. The magnetic flux leakage rate of target surface increases 5 times, and the magnetic flux leakage rate increases with the prolongation of heat treatment holding time. The optimal heat treatment holding time is obtained. After heat treatment, the transformation of CO CR TA alloy and the formation of {1210} and {1010} linear texture are the basic reason for the increase of magnetic flux leakage rate.
Co CR TA alloy itself is a kind of ferromagnetic material with high permeability. During magnetron sputtering, most of the magnetic field passes through the target from the inside. Due to the serious magnetic shielding, the magnetic field passing through the target surface is very small, which makes it impossible to carry out magnetron sputtering and become a very low efficiency two pole sputtering. The deposition rate of the film is greatly reduced and the substrate heats up sharply, which is impossible to connect in production Received. In the process of magnetron sputtering of magnetic thin films, there is a problem that ferromagnetic targets are hard to be sputtered normally. From the perspective of target preparation, one of the solutions is to improve the target preparation process and the target surface magnetic flux leakage rate (PTFs, pass through flux). In this paper, based on the improvement of the target preparation process, the differential scanning calorimetry (DSC) method is used to analyze the co CR TA alloy samples. The phase structure and the value of the PTFs of the co CR TA alloy under different heat treatment systems, as well as the texture of the rolling and heat treatment states are studied. The phase structure, the texture and the PTFs of the target surface are discussed The relationship between values.
1. Experiment
In this experiment, 99.9% Co bars, Cr blocks and Ta bars were used as raw materials, and CO: Cr: TA was proportioned according to the atomic ratio of 82:14:4. The prepared raw materials were put into a 10 kg vacuum induction furnace for smelting, the vacuum degree was 0.1 PA when smelting, after full melting, they were refined and cast into ingots; the ingots were forged and rolled into ingots of the specified size by multi fire forging, and the temperature of forging and rolling were 1230 ℃
2. The temperature of final forging and rolling is more than 1200 ℃, the cooling mode is air cooling, the total deformation of forging and rolling is more than 50%. The size of rolling plate is 190 mm × 200 mm × 10 mm, four groups in total. One group is kept in the original state for comparison; the other three groups are put into the medium temperature box type resistance furnace for heat preservation, the temperature is 895 ℃, protected by argon, the heat preservation time is 6, 12, 24 hours respectively, and after the heat preservation time, the rolling plate is quickly taken out of the resistance furnace and put into the water tank containing a large amount of room temperature water for quenching; then the four groups of rolling plates are respectively machined to produce a Φ 180 × 8 mm target material, and the PTFs are measured, Then take 10 mm × 10 mm × 10 mm and 16 (along the rolling direction) × 14 mm × 10 mm samples from the position near the target to do X-ray diffraction (XRD) and texture measurement. XRD was measured by Philips instrument, model: x'pert pro, Co-K α ray, step 0.0083556 °, scanning mode is continuous scanning, angle range is 20 ° ~ 120 °. The texture was measured by Siemens d5000-xrd, Cu Target and monochromator. Take the original rolling plate for DSC analysis, the instrument used is: Netzsch DSC 404c, the heating rate is 10 ℃ / min, the temperature range is 26 ~ 1300 ℃. Sypris is used as the measuring instrument for missing PTF, model: model 6010 Gauss / Tesla meter, and astm1 is used as the measuring standard.
3. Conclusion
(1) Co CR TA alloy has martensitic transformation. 864.9 ℃ is the starting temperature of transformation, and 1193 ℃ is the ending temperature.
(2) After heat treatment near the transformation point, martensitic transformation took place in CO CR TA alloy. The main phase changed from CO phase of FCC to co phase of HCP. The optimum heat treatment holding time was 12 h;
(3) After heat treatment near the transformation point, the co CR TA alloy forms two kinds of linear textures, which are close to {1210} and {1010}. The c axis of the two textures tends to be parallel to the rolling surface;
(4) After heat treatment, the transformation of the alloy and the formation of {1210} and {1010} linear texture lead to the decrease of the permeability along the normal direction of the target surface, which is the basic reason for the increase of the value of the PTFs.
On 2018-08-08 11:45:46
