N.B. Dhokey; A.G. Jadhav; S.S. Nimbalkar; V. Nimbalkar
Abstract
The composite material is an emerging opportunity for improving the loss factor. In the present context, AA7075 was fabricated in induction furnace using elemental addition such as Zn, Mg and Cu and ex-situ reinforcement of 10wt. % graphite particulates with three types of composites viz 3 to 10 μm ...
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The composite material is an emerging opportunity for improving the loss factor. In the present context, AA7075 was fabricated in induction furnace using elemental addition such as Zn, Mg and Cu and ex-situ reinforcement of 10wt. % graphite particulates with three types of composites viz 3 to 10 μm (C1), 53 to 66 μm (C2) and 106 to 150 μm (C3). The melt was poured at 780 o C and cast into the steel mold then hot forged at a strain rate of 3- 5x10-3 s-1 in three stages with net cross-section reduction in the range of 30-33%. Solutionizing at 470 o C was followed by artificial aging at 120 o C. Characterization was carried out by SEM and DMA at two selected frequencies 0.1Hz and 1Hz over the temperature range of 30 to 250 o C. Significant improvement in storage modulus (E’) and loss modulus (E”) noticed in C2 as compared to the C1, C2 and monolithic alloy. A threshold value of the volume to the surface of graphite reinforcement has arrived for an improved loss factor. A generalized experimental model formulated to account for 12 influencing parameters and the significance of damping capacity with the response to graphite content has been established.
Anatoliy Klopotov; Victor Gunther; Ekaterina Marchenko; Gulsharat Baigonakova; Timofey Chekalkin; Ji-soon Kim; Ji-hoon Kang
Abstract
Within the wide family of shape memory alloys (SMAs), TiNi-based alloys are characterized by unique characteristics, with good workability in the martensite phase and good resistance to corrosion and fatigue. In the nearest future, TiNi-based SMAs are expected the second birth to begin regarding their ...
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Within the wide family of shape memory alloys (SMAs), TiNi-based alloys are characterized by unique characteristics, with good workability in the martensite phase and good resistance to corrosion and fatigue. In the nearest future, TiNi-based SMAs are expected the second birth to begin regarding their practical application, especially in creating a new material generation showing enhanced characteristics for clinical goals. Such a kind of expectations is naturally supposed to make a search among alloying elements for TiNi-based SMAs, as well as studies of adjacent effects in order to improve material properties. The objective of the work is to investigate the effect of heat treatment on the structure and properties of the quaternary Ti50Ni47.7Mo0.3V2 SMA, as potentially promising for medical devices. Specimens were prepared and annealed at 723, 923, 1123 K for 1 h. It was found that the studied alloy was in a multiphase state: TiNi-based intermetallic in three crystallographic modifications (austenite B2-phase and martensitic R- and B19¢structures) and secondary Ti2Ni(V) phase. The increase of the annealing temperature doesn't affect the martensite transformation (MT) sequence B2«R«B19′, but leads to a growth in lattice parameter of the parent phase. The most remarkable effect on the studied alloy was at 723 K. Volume fraction of Ti2Ni(V) precipitates in the structure was also maximum. It owes their presence to the shift of the MT points toward the lower temperature range. The temperature vs resistivity r(T) curves show a characteristic shape, which is typical for TiNi-based SMAs with a two-step nature of the B2«R«B19′ MT.
Hirotaka Tanabe; Keiji Ogawa; Yui Izumi; Motoyuki Nishizawa; Tohru Takamatsu; Heisaburo Nakagawa
Abstract
A new surface modification method “laser quenching after coating” using a high power diode laser equipped with a 2-dimensional galvano-scanner unit was developed to process a larger area of ceramic coated steel uniformly and efficiently. The laser irradiation tests for 3 kinds of ceramic-coated ...
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A new surface modification method “laser quenching after coating” using a high power diode laser equipped with a 2-dimensional galvano-scanner unit was developed to process a larger area of ceramic coated steel uniformly and efficiently. The laser irradiation tests for 3 kinds of ceramic-coated steels: CrAlN, TiAlN and CrN, were carried out with the scanning laser, and the appropriate irradiation conditions to achieve the uniformly quenched substrate without any surface damage were clarified for these ceramic-coated steels. The area of the substrate surface wider than the laser spot size could be easily quenched by the scanning laser. The adhesive strength, the film hardness of the laser-irradiated regions and the deformation caused by laser irradiation were evaluated. Laser quenching with the scanning laser can effectively improve the adhesive strength and substrate hardness without any detrimental effect on the film hardness of the ceramic-coated specimens. In the deformation of the laser-irradiated specimens, two features were recognized; one is the bending, and the other is the expansion of laser-irradiated part. It was found that the deformation of ceramic-coated steel by laser irradiation under the same heat input condition does not depend on the kind of ceramic thin film but on the steel type of the substrate. It was concluded that “laser quenching after coating” with scanning laser could easily improve the adhesive strength and substrate hardness without any detrimental effect on the film hardness of large surface areas in the tested all types of ceramic-coated specimens.
