• Journal of Welding and Joining
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• v.31 no.5
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• pp.64-70
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• 2013

The joining of Ti and SUS304 dissimilar metals is one of the effective measures to save rare metal. But Ti and SUS304 have differences in materials properties, and Ti and Fe intermetallic compounds such as TiFe and $TiFe_2$ are easily formed in weld fusion zone between Ti and SUS304. Nevertheless, in this study, full penetration lap dissimilar welding of Ti and SUS304 using single-mode fiber laser with ultra-high welding speed was tried, and it was found out that ultra-high welding speed could control the generation of intermetallic compound. To recognize the formation of intermetallic phase in the weld fusion zone and the compound zone of interface weld area were observed and analyzed using energy dispersive X-ray spectroscopy (EDX). And it was confirmed that the ultra-high welding speed could reduce amount of intermetallic compounds, but the intermetallic compounds were existed in the weld fusion zone under the all conditions.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.05a
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• pp.58-58
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• 1994

• Proceedings of the Materials Research Society of Korea Conference
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• 2001.11a
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• pp.107-107
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• 2001

• Journal of Korea Foundry Society
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• v.28 no.2
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• pp.69-73
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• 2008

In the present study, microstructural evolution and mechanical properties of Ti-Fe-Sn ultrafine eutectic alloys have been investigated. Ultrafine eutectic microstructure consisting of a mixture of ${\beta}$-Ti solid solution and TiFe intermetallic compound homogeneously formed in $(Ti_{70.5}Fe_{29.5})_{100-x}Sn_x$ alloys with x = 0, 1 and 3. Addition of Sn is effective to modify the eutectic colony into the spherical shape with decreasing the lamellar spacing and colony size. This results in enhancing the macroscopic plasticity up to 3.1% of the Ti-Fe-Sn ultrafine eutectic alloys.

• Korean Journal of Materials Research
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• v.14 no.10
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• pp.688-695
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• 2004

The capacitor contact barrier(CCB) layers have been introduced in the FeRAM integration to prevent the Pt/Al reaction during the back-end processes. Therefore, the interdiffusion and intermetallic formation in $Pt(1500{\AA})/Al(3000{\AA})$ film stacks were investigated over the annealing temperature range of $100\sim500^{\circ}C$. The interdiffusion in Pt/Al interface started at $300^{\circ}C$ and the stack was completlely intermixed after annealing over $400^{\circ}C$ in nitrogen ambient for 1 hour. Both XRD and SBM analyses revealed that the Pt/Al interdiffusion formed a single phase of $RtAl_2$ intermetallic compound. On the other hand, in the presence of TiN($1000{\AA}$) barrier layer at the Pt/Al interface, the intermetallic formation was completely suppressed even after the annealing at $500^{\circ}C$. These were in good agreement with the predicted effect of the TiN diffusion barrier layer. But the conventional TiN CCB layer could not perfectly block the Pt/Al reaction during the back-end processes of the FeRAM integration with the maximum annealing temperature of $420^{\circ}C$. The difference in the TiN barrier properties could be explained by the voids generated on the Pt electrode surface during the integration. The voids were acted as the starting point of the Pt/Al reaction in real FeRAM structure.

• Korean Journal of Metals and Materials
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• v.50 no.7
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• pp.477-485
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• 2012

The effect of aging heat treatment on microstructure evolution of the Ti-6Al-4Fe-0.25Si alloy with an initial microstructure of an elongated alpha was investigated. Aging treatments of the samples were carried out at $550^{\circ}C$ for up to 100 hours. The microstructure of the 5 hours heat-treated sample consisted of alpha grains, beta matrix and some TiFe intermetallic compounds that were precipitated from the beta matrix. Increasing the aging time to 10 hours, most of the beta matrix was decomposed to very fine alpha grains (${\sim}0.5{\mu}m$) and TiFe, and thus the volume fraction of the beta matrix was significantly decreased. EBSD analysis revealed that newly formed tertiary-alpha-grains in the vicinity of TiFe had high angle boundaries with respect to the primary and secondary alpha grains. As a result of these phase transformations during aging, the fraction of the alpha/alpha grain boundary was increased while that of the alpha/beta phase boundary was decreased.

• Transactions of Materials Processing
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• v.20 no.2
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• pp.140-145
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• 2011

The aim of the present study is to derive optimized post heat treatment temperatures to get a proper formability for Ti/STS409L/Ti clad materials. These clad materials were fabricated by cold rolling followed by a post heat treatment process for 10 minutes at temperatures ranging from $500^{\circ}C$ to $850^{\circ}C$. The microstructure of the interface was observed using a Scanning Electron Microscope(SEM) and an Energy Dispersive X-ray Analyser(EDX) in order to investigate the effects of post heat treatment on the bonding properties of the Ti/STS409L/Ti clad materials. Diffusion bonding was observed at the interfaces with a diffusion layer thickness increasing with the post heat treatment temperature. The diffusion layer was composed of a type of(${\varepsilon}+{\zeta}$) intermetallic compound containing additional elements, namely, Fe, Ti and Ni. The micro Knoop hardness of the Ti/STS409L interfaces was found to increase with heat treatment up to $800^{\circ}C$ and then decrease for temperatures rising up to $850^{\circ}C$. The tensile strength was shown to decrease for heat treatment temperature increasing to $750^{\circ}C$ and then increase rapidly for temperature rising up to $850^{\circ}C$. A post heat treatment temperature range of $700{\sim}750^{\circ}C$ was found to optimize the formability of Ti/STS409L/Ti clad materials.

• Korean Journal of Materials Research
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• v.27 no.10
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• pp.557-562
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• 2017

The microstructural evolution and modulation of mechanical properties were investigated for a $Ti_{65}Fe_{35}$ hypereutectic alloy by addition of $Bi_{53}In_{47}$ eutectic alloys. The microstructure of these alloys changed with the additional BiIn elements from a typical dendrite-eutectic composite to a bimodal eutectic structure with primary dendrite phases. In particular, the primary dendrite phase changed from a TiFe intermetallic compound into a ${\beta}$-Ti solid solution despite their higher Fe content. Compressive tests at room temperature demonstrated that the yield strength slightly decreased but the plasticity evidently increased with an increasing Bi-In content, which led to the formation of a bimodal eutectic structure (${\beta}$-Ti/TiFe + ${\beta}$-Ti/BiIn containing phase). Furthermore, the (Ti65Fe35)95(Bi53In47)5 alloy exhibited optimized mechanical properties with high strength (1319MPa) and reasonable plasticity (14.2 %). The results of this study indicate that the transition of the eutectic structure, the type of primary phases and the supersaturation in the ${\beta}$-Ti phase are crucial factors for controlling the mechanical properties of the ultrafine dendrite-eutectic composites.

• Journal of Welding and Joining
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• v.17 no.5
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• pp.107-115
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• 1999

The objective of this research was to study the formation of the thick hardened layer with the addition of metal powder(Cu) and ceramics powders(TiC) on the aluminum 5083 alloys by plasma transferred arc process(PTA process) and to characterize the effect of overlaying conditions on the overlaid layer formation. This was followed by investigating the microstructures of the overlaid layers and mechanical properties such as hardness and wear resistance. The overlaid layer containing copper powder was alloyed and intermetallic compound($CuAl_2$) was formed. The overlaid layers with high melting point TiC powders, however, did not react with base metal. Wear resistance of the alloyed layer was remarkably improved by the formation of $CuAl_2$, precipitate phase, which prevented wear of base aluminum alloys and at higher wear speed, accelerated sliding of the counter part. Wear resistance of the composite layer was also remarkably improved because TiC powder act as a load barring element and Fe debris fragments detached from the counter part act as a solid lubricant on the contact surface.