2nd Annealing Research Articles

Extraordinary simultaneous enhancement of the coercivity and remanence of dual alloy HRE‐free Nd‐Fe‐B sintered magnets by post‐sinter annealing

• Both the remanence and coercivity are improved after the 2nd annealing process. • The coercivity is hugely increased from 10.09 kOe for the as-sintered sample to 17.19 kOe for the 2nd annealed magnet, with a significant increment of 70.37%. • The matrix grains are enveloped by a (Pr,Nd,Cu,Ga)-enriched layer after the 2nd annealing process. • HRE-free Nd-Fe-B sintered magnets with excellent comprehensive magnetic properties were manufactured by Pr-Fe-Ga boundary addition. Post-sinter annealing process plays an important role in the microstructures and magnetic properties of the Nd-Fe-B sintered magnets. In this paper, systematically investigated are the magnetic properties and microstructures of the as-sintered and post-sinter annealed Nd-Fe-B magnets with Pr-Fe-Ga boundary addition. Two choice consecutive annealing methods are adopted at high and low temperatures, namely the 1 st annealing at 880 ºC for 2 h and then the 2 nd annealing at 440 ºC for 3 h. It is exceptional to find out that both the remanence and coercivity are improved after 2 nd annealing process for this type of magnet. The coercivity is hugely increased from 10.09 kOe for the as-sintered sample to 17.19 kOe for the 2 nd annealed magnet, with a significant increment of 70.37% in coercivity. The extraordinary magnetic properties of B r =14.44 kGs, H cj =17.19 kOe and ( BH ) max =51.08 MGOe are obtained for the designated Nd-Fe-B sintered magnets without heavy rare earth (HRE) elements manufactured by dual alloy method. The Curie temperature is monotonically decreased from 634 K to 602 K while the c -axis alignment degree is optimized after annealing. Microstructural observation and analysis indicate that the elemental distribution patterns are altered after the 2 nd annealing. The diffusion of the aggregate (Pr,Nd,Cu,Ga)-rich phase from triple junctions into the grain boundary regions is ascribed to the formation of thin and continuous grain boundary layer, which is critical to improve the microstructures and magnetic properties.

Effect of Initial Texture on the Evolution of Texture and Stored Energy during Recrystallization of Interstitial Free Steel

By applying a double cold rolling and annealing treatment, the evolution of the α and γ fiber components differed from the ones observed in conventional processing. This is attributed to the difference of the initial texture. An increased reduction of stored energy of the {111}<112> component was found by monitoring the change of the stored energy during annealing, indicating that the onset of the nucleation stage of recrystallization by relaxation and annihilation of dislocations occurred mainly on the {111}<112> component with its higher stored energy. The detailed texture evolution of the double cold rolled specimen during 2nd annealing is described by coupling the theory of oriented nucleation and orientation pinning, which is experimentally confirmed by OIM scan.

高炭素冷延鋼板の延性におよぼすミクロ組織の影響

The effect of void initiation due to microstructural factors, including the size and distribution of spheroidized cementite and ferrite grain size, on elongation in JIS S35C and JIS S65C high carbon cold-rolled steel sheets were investigated.Among mechanical properties after 2nd annealing, yield strength (YS) and tensile strength (TS) both increased as cold-rolling reduction increased, and total elongation (T.EI.) also increased simultaneously. This resulted in large improvement in the TS-T.EL. Balance. As mirostructural changes in this case, with the increase in cold-rolling reduction, the ferrite grain diameter decreased and cementite on the ferrite grain boundary increase.According to the results of a detailed study of S35C, when the microstructure was composed of fine ferrite and cementite on the ferrite grain boundary, elongation was high. In the tensile deformation process, destruction of the grain boundary cementitie was frequently observed. Voids were initiated from these points of origin, and fracture then occurred rapidly. On the other hand, when the microstructure was composed of coarse ferrite grains and fine cementite existed within the ferrite grain, elongation was low. In particular, uniform elongation was markedly decreased. In this deformation process, voids were initiated from cementite on deformation bands, then joined to form cracks, resulting in fracture.

Study on the Variations of Microstructures and Domain Structures of Bi3.35La0.85Ti3O12 Ferroelectric Thin Films Formed by Two-Step Rapid Thermal Annealing (RTA) Process Utilizing Piezoresponse Force Microscope (PFM)

Recently, La-substituted Bi4Ti3O12 (BLT) has been widely studied as a candidate material for FeRAM due to its superior properties like high fatigue endurance with relatively lower crystallization temperature. In this study, we attempted to examine ferroelectric properties of various BLT thin films that were made using two-step rapid thermal annealing (RTA) process. The microstructure of BLT thin film is appeared as a critical factor to maximize ferroelectric properties. We found that the 2nd annealing temperature in two-step RTA process played an important role in determining the crystalline orientation of BLT thin films. Grain orientations of the BLT thin films were interpreted based on x-ray diffraction (XRD) in conjunction with piezoresponse images that were obtained utilizing piezoresponse force microscope (PFM). In addition, the results were correlated with the hysteresis loops.

Stress Enhanced Arsenic Diffusion In Titanium Salicided Junctions By Implantation Into C49 TiSi2 and Rapid Thermal Annealing

AbstractWe studied reverse leakage current in n+/p titanium-salicided shallow junctions using C49 Ti-silicide as a diffusion source. After Ti deposition, rapid thermal annealing (RTA) was performed to form the C49 Ti-silicide. Subsequently, arsenic ions were implanted and a 2nd RTA was carried out at 850 °C to form the low resistivity C54 Ti-silicide. In spite of no drive-in process following the 2nd annealing, the implanted As diffused well into Si substrate and the reverse leakage current of the n+/p junctions was reduced to two orders of magnitude lower. Since the high chemical affinity of As to Ti-silicide trapped the dopant in the silicide, it has been known that Ti or Ti-silicide cannot be used as a diffusion source. However, in this work, we found that the C49 Ti-silicide acted as a diffusion source of As ions. The reason of fast diffusivity is attributed to the generation of high tensile stress induced by As implantation.

New low temperature processing of sol-gel SrBi2Ta2O9 thin films

A new low temperature processing method to prepare SrBi2Ta2O9 thin films is proposed. These thin films were prepared on Pt/Ta/SiO2/Si substrates by a sol-gel method, and their structural and electrical properties were investigated. Films were annealed before and after the top Pt electrode deposition, respectively. The 1st annealing was performed in a 760 Torr-oxygen ambient at 600°C for 30 min; the 2nd annealing was performed in a 5 Torr-oxygen ambient at 600 °C for 30 min. The films were well crystallized and fine-grained after the 2nd annealing. The electrical characteristics of the 200-nm-thick film obtained by this new process, i.e., remanent polarization (Pr), coercive field (Ec), and the leakage current density (II), were as follows; Pr = 8.5 μC/cm2, Ec=30 kV/cm, IL=1×10−7 A/cm2 (at 3V). This new processing is very attractive for highly integrated ferroelectric nonvolatile memory applications.

New Low Temperature Processing of Sol-Gel SrBi2Ta2O9 Thin Films

A new low temperature processing method for preparation of SrBi2Ta2O9 thin films is proposed. These thin films were prepared on Pt/Ta/ SiO2/Si substrates by a sol-gel method, and their structural and electrical properties were investigated. Films were annealed before and after the top Pt electrode deposition. The 1st annealing was performed in a 760 Torr oxygen atmosphere at 600° C for 30 min, and the 2nd annealing was performed in a 5 Torr oxygen atmosphere at 600° C for 30 min. The films were well crystallized and fine grained after the 2nd annealing. The electrical properties of the 200-nm-thick film obtained using this new processing method, i.e., the remanent polarization (P r), coercive field (E c), and leakage current density (I L), were as follows: P r=8.5 µ C/cm2, E c=30 kV/cm, and I L=1×10-7 A/cm2 (at 150 kV/cm). This new processing method is very attractive for highly integrated ferroelectric nonvolatile memory applications.

Ｂｉ（Ｐｂ）系超伝導多結晶薄膜の諸特性と磁電変換効率

The Bi-Pb-Sr-Ca-Cu-O thin films with different composition were prepared on MgO single crystal (100) by rf magnetron sputtering using multi targets:Bi0.5Pb0. ?? Oz, CaCu0.75Oz, SrCu0.75Ox. The obtained films were two-step-annealed to crystallize. The crystalline phase of the annealed films were greatly depended on the 2nd annealing temperature. Low temperature(about 820°C) annealing films were composed of C-axis orintated low-Tc phase (Bi(Pb)2Sr2Ca1Cu2Ox). The high-Tc phase(Bi(Pb)2Sr2Ca2Cu2Ox) produced by higher temperature annealing and the films annealed at about 840°C contained both of C-axis orientated low-Tc phase and high-Tc phase. Moreover high temperature (about 850°C) annealing films were composed of C-axis orientated high-Tc phase. From the SEM photograhs of the films annealed at low temperature and at high temperature region. the plate-like crystals of low-Tc and high-Tc phase stacked on each other with C-axis orientation (orientation structure). However, the films annealed in temperature region between them were composed of the mixture of the plate-like crystals with C-axis orientation and with almost perpendicular to the substrate (mixed structure). The sensitivity in magnetic field showed low for the films with orientation structure. On the other hand, it showed high for the films with mixed structure. It implied that the weak-link well produced at grain boudary in the mixed structure.