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Efect of heat treatment parameters on microstructure evolution, tensile strength, wear resistance, and fracture behavior of Ni-Ti multilayered composites produced by cross‑accumulative roll bonding

Ye Qing, Li Xuejun, Tayyebi Moslem, Assari Amir Hossein, Polkowska Adelajda, Lech Sebastian, Polkowski Wojciech, Tayebi Morteza

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 1

art. no. e27, 2023

EN

The last decades have seen a huge growth in the investigation of intermetallic compounds at the interfaces of laminated composites due to their useful features. In this research, efects of the formation of intermetallic compounds on tensile properties and wear resistance of Ni/Ti composites produced by cross-accumulative roll bonding (CARB) process have been examined at diferent annealing times and temperatures. Scanning electron microscopy (SEM) images demonstrated that the layers were well bonded together, but Ni layers experienced instabilities in light of plastic deformation. The EBSD results showed lamellar structure and crystallographic texture on Ti and Ni layers during plastic deformation. According to X-ray difractometer (XRD) and energy-dispersive spectrometer (EDS) analyses, NiTi2 and NiTi were present in all annealed samples. The thickness of intermetallic compounds grew with an increase in annealing temperature and time. However, this growth led to a decrease in tensile strength while the values of elongation fuctuated. Based on the results of the wear test, the composite became more resistant to wear when the thickness of intermetallic layers increased. The surfaces of these layers with less roughness and lower coefcients of friction facilitated the movement of steel pin on samples during the wear test. Furthermore, wear mechanisms of adhesion, abrasion, and delamination were observed, and they were more noticeable at higher loads and lower annealing temperatures and times.

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Elevated-temperature tensile deformation and fracture behavior of particle-reinforced PM 8009Al matrix composite

Chen Shuang, Chen Guoqiang, Gao Pingping, Liu Chunxuan, Wu Anru, Dong Lijun, Huang Zhonghua, Ouyang Chun, Zhang Hui

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 5

art. no. e138846

EN

Tensile tests of 8009Al alloy reinforced with SiC and Al₂O₃ particles fabricated by powder metallurgy (PM) were conducted at temperatures of 250–350°C and strain rates of 0.001–0.1 s⁻¹. The ultimate tensile strength and yield strength of the samples decreased while the temperature and strain rate increased. The elongation slightly decreased at first and then increased with growing temperature because of the medium-temperature brittleness of the alloy matrix. When the strain rate was 0.1 s⁻¹, the elongation of the 8009Al/Al₂O₃ composites always decreased with an increase in temperature because of the poorly coordinated deformation and weak bonding between the matrix and Al₂O₃ particles at such a high strain rate. The work-hardening rates of the composites sharply increased to maxima and then decreased rapidly as the strain increased. Meanwhile, the 8009Al/SiCₚ composites displayed superior UTS, YS, elongation, and work-hardening rates than those of the 8009Al/Al₂O₃ composites under the same conditions. Compared to 8009Al alloys reinforced with spherical Al₂O₃ particle, 8009Al alloys reinforced with irregular SiC particles exhibited a better strengthening effect. The fracture mechanism of the 8009Al/SiCₚ composites was mainly ductile, while that of the 8009Al/Al₂O₃ composites was primarily debonding at the matrix–particle interfaces in a brittle mode.

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In-situ Observation of High-Temperature Fracture Behaviour of 347 Stainless Steel Subjected to Simulated Welding Process

Ko Seok-Woo, Park Hyeonwoo, Yoo Il, Kim Hansoo, Lee Joonho, Hwang Byoungchul

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 4

1019--1022

EN

In-situ study on the high-temperature fracture behaviour of 347 stainless steel was carried out by using a confocal laser scanning microscope (CLSM). The welding microstructures of the 347 stainless steel were simulated by subjecting the steel specimen to solution and aging treatments. Undissolved NbC carbides were present within grains after solution treatment, and M23C6 carbides were preferentially formed at grain boundaries after subsequent aging treatment. The M23C6 carbides formed at grain boundaries worked as stress concentration sites and thus generated larger cracks during high-temperature tensile testing. In addition, grain boundary embrittlement was found to be a dominant mechanism for the high-temperature fracture of the 347 stainless steel because vacancy diffusion in the Cr-depleted zones enhances intergranular fracture due to the precipitation of M23C6 carbides at grain boundaries.

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Experimental Study On Fracture Property Of Tapered Double Cantilever Beam Specimen With Aluminum Foam

Kim Y. C., Kim S. S., Cho J. U.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2B

1459--1462

EN

It is indispensable to evaluate fracture energy as the bonding strength of adhesive at composite material with aluminum foam. This specimen is designed with tapered double cantilever beam by British standards (BS 7991 and ISO 11343). 4 kinds of specimens due to m values of 2, 2.5, 3 and 3.5 are manufactured and compared each other with the experimental results. Adhesive fracture energy is calculated from the formulae of British standards. The value of m is the gradient which is denoted as the length and the height of specimen. As m becomes greater at static experimental result, the maximum load becomes higher and the displacement becomes lower. And the critical fracture energy becomes higher. As m becomes less at fatigue experimental result, the displacement becomes higher and the critical fracture energy becomes higher. Fracture behavior of adhesive can be analyzed by this study and these experimental results can be applied into real field effectively. The stability on TDCB structure bonded with aluminum foam composite can be predicted by use of this experimental result. Adhesive fracture energy is calculated from the formulae of British standards. Based on correlations obtained in this study, the fracture behavior of bonded material would possibly be analyzed and aluminum foam material bonded with adhesive would be applied to a composite structure in various fields, thereby analyzing the mechanical and fracture characteristic of the material.