• Nuclear Engineering and Technology
• /
• v.52 no.10
• /
• pp.2299-2305
• /
• 2020

Zr alloy specimens were coated with Cr-Al alloy to enhance their resistance to oxidation. The coated samples were oxidized at 1200 ℃ in a steam environment for 300 s and showed extremely low oxidation when compared to uncoated Zr alloy specimens. The microstructure and elemental distribution of the oxides formed on the surface of Cr-Al alloys have been investigated by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). A very thin protective layer of Cr₂O₃ formed on the outer surface of the Cr-Al alloy, and a thin Al₂O₃ layer was also observed in the Cr-Al alloy matrix, near the surface. Our results suggest that these two oxide layers near the surface confers excellent oxidation resistance to the Cr-Al alloy. Even after exposure to a high temperature of 1200 ℃, inter-diffusion between the Cr-Al alloy and the Zr alloy occurred in very few regions near the interface. Analysis of the inter-diffusion layer by high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS) measurement confirmed its identity as Cr₂Zr.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.23 no.3
• /
• pp.240-244
• /
• 2010

The surface segregation and surface order near the order-disorder phase transition of FeCo alloy was studied through Monte Carlo simulation of an Ising type model Hamiltonian. The results showed that the proper choice of Hamiltonian parameters could reproduce the recent observation of surface order above the transition temperature and that the field term played dominant role.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.12
• /
• pp.126-134
• /
• 2003

In order to investigate the effect of surface treatment in Aluminium alloy and Titanium alloy which are used to armor material during ballistic impact, a ballistic testing was conducted. Anodizing was used to achieve higher surface hardness of Aluminium alloy and Iron plating in PVD(Physical Vapor Deposition) method was used to achieve higher surface hardness of Titanium alloy. Surface hardness test were conducted using a Micro victor's hardness tester. Ballistic resistance of these materials was measured by protection ballistic limit(V-50), a statical velocity with 50% probability penetration. Fracture behaviors and ballistic tolerance, described by penetration modes, are respectfully observed from the results of V-50 test and Projectile Through Plates (PTP) test at velocities greater than V-50. PTP tests were conducted with 0$^{\circ}$obliquity at room temperature using 5.56mm ball projectile. V-50 tests were conducted with 0$^{\circ}$obliquity at room temperature with projectiles that were able to achieve near or complete penetration during PTP tests. Surface hardness, resistance to penetration. and penetration modes of surface treated alloy laminates are compared to those of surface non-treated alloy laminates. A high speed photography was used to analyze the dynamic perforation phenomena of the test materials.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2000.02a
• /
• pp.164-164
• /
• 2000

Since Au-Pt alloys have various atomic structures depending upon composition and annealing temperature, it is very interesting to investigate the electronic structures of alloys. We studied the changes of the electronic structure I the Au-Pt alloys by x-ray absorption near edge spectroscopy (XANES). Two kinds of Au-Pt alloy samples were prepared by arc melting methods and ion-beam-mixing technique. The Pt L2, 3-edge and Au L2, 3-edge X-ray absorption spectra (XPS) were measured with the electron yield mode detector at the 3C1 beam line of the Pohang Light Source (PLS). It was found that there was a substantial decrease in the area of the Pt L2, 3 white lines compared with that of pure Pt. The observed decrease in white line area was attributed to an increase in the number of pure Pt. The observed decrease in white line area was attributed to an increase in the number of 5d-electrons at the Pt site upon alloy formation. However, the Au L2, 3 edge spectra for Au-Pt alloys are all similar to that of pure Au. This implies that the 5d hole count of Au is not changed by alloy formation with Pt.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1994.06a
• /
• pp.147-147
• /
• 1994

• Proceedings of the Korean Magnestics Society Conference
• /
• 2013.05a
• /
• pp.15-16
• /
• 2013

Magnetization behavior of ultra thin $Fe_xCo_{1-x}$ alloy (where x varies from 0 to 100) has been investigated as functions of composition on Cr (100) substrate by using in situ surface magneto optical Kerr effect (SMOKE). It's always show in plane uniaxial magnetic anisotropy at room temperature (RT) & Low temperature (LT). It is observed that composition dependent coercive force maximum at about 30 at % Co and 70 at % Co atomic ratio and minimum near equiatomic site. The relative magnetic moments as composition variation also show magnetization collapse near equiatomic site. The magnetization behaviors of Fe-Co alloy on Cr (100) due to composition varies are supported the order-disordering as well as structural stability bcc (ferromagnetic)/fcc (anti-ferromagnetic) phase stability magnetism.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.820-824
• /
• 1997

In order to investigate the effect of surface treatment(Anodizing) and rolling in Al 5083-H131 alloy, ballistic testing was conducted. Ballistic resistance of these materials. was measured by protection ballistic limit(V$_{50}$), a statical velocity with 50% probability for incomplete penetration. Fracture behaviors and ballistic tolerance, described by penetration modes, are observed respectfully, resulting from V$_{50}$ test and Projectile Through Plates(PTP) test at velocities greater than V$_{50}$. PTP tests were conducted with 0$^{\circ}$obliquity at room temperature were also conducted with projectiles that were able to achieve near or complete penetration during PTP tests. Resistance to penetration, and penetration modes of Al 5052-H34 alloy, compared to those of Al 5083-H131 alloy.alloy.

• Proceedings of the KSME Conference
• /
• 2001.06a
• /
• pp.567-572
• /
• 2001

In order to investigate the fracture behaviors(penetration modes) and resistance to penetration during ballistic impact of Titanium alloy laminates and nitrified Titanium alloy laminates which were treated by PVD(Physical Vapor Deposition) method, ballistic tests were conducted. Evaporation, sputtering, and ion plating are three kinds of PVD method. In this research, Ion plating was used to achieve higher surface hardness and surface hardness test were conducted using a Micro vicker's hardness tester. Resistance to penetration is determined by the protection ballistic limit($V_{50}$), a statistical velocity with 50% probability for complete penetration. Fracture behaviors and ballistic tolerance, described by penetration modes, are respectfully observed at and above ballistic limit velocities, as a result of $V_{50}$ test and Projectile Through Plates (PTP) test methods. PTP tests were conducted with $0^{\circ}$ obliquity at room temperature using 5.56mm ball projectile. $V_{50}$ test with $0^{\circ}$ obliquity at room temperature were conducted with projectiles that were able to achieve near or complete penetration during PTP tests. Surface hardness, resistance to penetration, and penetration modes of Titanium alloy laminates are compared to those of nitrified Titanium alloy laminates.

• Journal of Korean Vacuum Science & Technology
• /
• v.6 no.2
• /
• pp.92-96
• /
• 2002

In this paper, we treated the Ni$_3$Al based alloy samples with intense pulsed ion beams (IPIB) at the beam parameters of 250KV acceleration voltage, 100 - 200 A/cm$^2$ current density and 60 u pulse duration. We simulated the thermal-mechanical process near the surface of Ni$_3$Al based alloy with our STEIPIB codes. The surface morphology and the cross-section microstructures of samples were observed with SEM, the composition of the sample surface layer was determined by X-ray Energy Dispersive Spectrometry (XEDS) and the microstructure on the surface was observed by Transmission Electron Microscope (TEM). The results show that heating rate increases with the current density of IPIB and cooling rate reached highest value less than 150 A/cm$^2$. The irradiation of IPIB induced the segregation of Mo and adequate beam parameter can improve anti-oxidation properly of IC6 alloy. Some craters come from extraneous debris and liquid droplets, and some maybe due to the melting of the intersection region of interphase. Increasing the pulse number enlarges average size of craters and decreases number density of craters.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.852-855
• /
• 2002

In order to investigate the fracture behaviors(penetration modes) and resistance to penetration during ballistic impact of surface hardening treated Aluminum, Titanium alloy laminates, ballistic tests were conducted. In this paper, Anodized Al 5083-H131 alloy laminates and nitrified Ti (Gr.2) alloy laminates were used to achieve higher surface hardness. Surface hardness test were conducted using a Micro victor's hardness tester and thickness of surface hardening treated specimens was measured by video microscope. Resistance to penetration is determined by the protection ballistic limit($V_50$), a statistical velocity with 50% probability far complete penetration. Fracture behaviors and ballistic tolerance, described by penetration modes, are respectfully observed at and above ballistic limit velocities, as a result of $V_50$ test and Projectile Through Plates (PTP) test methods. PTP tests were conducted with $0^{\circ}$ obliquity at room temperature using 5.56mm ball projectile. $V_50$ tests with $0^{\circ}$ obliquity at room temperature were conducted with projectiles that were able to achieve near or complete penetration during PTP tests.