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Author Martinez, C.; Briones, F.; Aguilar, C.; Araya, N.; Iturriza, I.; Machado, I.; Rojas, P. doi  openurl
  Title Effect of hot pressing and hot isostatic pressing on the microstructure, hardness, and wear behavior of nickel Type
  Year 2020 Publication Materials Letters Abbreviated Journal Mater. Lett.  
  Volume 273 Issue Pages 127944  
  Keywords MECHANICAL-PROPERTIES; RESISTANCE; NANO  
  Abstract Nanocrystalline Ni (Ni-nc) obtained by mechanical milling may present improved mechanical properties paired with high abrasion resistance. Different sintering processes were used to consolidate Nanocrystaline Ni: hot pressed (HP) and hot-isostatic pressed (HIP). The microstructure, mechanical properties, and tribological were evaluated to compare the processes. X-ray diffraction patterns showed that HIP-consolidated specimens had larger crystallite sizes and 37% less microstrain when compared to the HP specimens. The nanohardness of the HIP specimens was also carried out and it was 50% lower than that of HP specimens, whereas its coefficient of friction found was 25% higher. These results show the advantages of the HP process over the HIP since the high pressure. The low sintering temperature of HP inhibited the grain growth, which leads excellent mechanical and tribological properties of Ni. (C) 2020 Elsevier B.V. All rights reserved.  
  Address  
  Corporate Author Thesis (up)  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0167-577X ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000538775300023 Approved  
  Call Number UAI @ alexi.delcanto @ Serial 1403  
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Author Guzman, D.; Aguilar, C.; Rojas, P.; Criado, J.M.; Dianez, M.J.; Espinoza, R.; Guzman, A.; Martinez, C. doi  openurl
  Title Production of Ag-ZnO powders by hot mechanochemical processing Type
  Year 2019 Publication Transactions of Nonferrous Metals Society of China Abbreviated Journal T. Nonferr. Metal. Soc.  
  Volume 29 Issue 2 Pages 365-373  
  Keywords Ag-ZnO; nanocomposite; electrical contact material; powder synthesis; milling  
  Abstract Ag-CdO composites are still one of the most commonly used electrical contact materials in low-voltage applications owing to their excellent electrical and mechanical properties. Nevertheless, considering the restriction on using Cd due to its toxicity, it is necessary to find alternative materials that can replace these composites. In this study, the synthesis of Ag-ZnO alloys from Ag-Zn solid solutions was investigated by hot mechanochemical processing. The hot mechanochemical processing was conducted in a modified attritor mill at 138 degrees C under flowing O-2 at 1200 cm(3)/min for 3.0 h. The microstructure and phase evolution were investigated using X-ray diffractometry, field emission gun scanning electron microscopy and transmission electron microscopy. The results suggest that it is possible to complete the oxidation of Ag-Zn solid solution by hot mechanochemical processing at a low temperature and short time. This novel synthesis route can produce Ag-ZnO composites with a homogeneous distribution of nanoscale ZnO precipitates, which is impossible to achieve using the conventional material processing methods. Considering the fact that the fundamental approach to improving electric contact material performance resides in obtaining uniform dispersion of the second-phase in the Ag matrix, this new processing route could open the possibility for Ag-ZnO composites to replace non-environmentally friendly Ag-CdO.  
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  Corporate Author Thesis (up)  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1003-6326 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000460293100015 Approved  
  Call Number UAI @ alexi.delcanto @ Serial 1404  
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Author Martinez, C.; Aguilar, C.; Briones, E.; Guzman, D.; Zelaya, E.; Troncoso, L.; Roja, P.A. doi  openurl
  Title Effects of Zr on the amorphization of Cu-Ni-Zr alloys prepared by mechanical alloying Type
  Year 2018 Publication Journal of Alloys and Compounds Abbreviated Journal J. Alloys Compd.  
  Volume 765 Issue Pages 771-781  
  Keywords BULK METALLIC GLASSES; SOLID-SOLUTION; CRYSTALLINE; FABRICATION; EVOLUTION; POWDERS; SYSTEM; NB; TI  
  Abstract This work presents the effects of high energy milling with different Ni and Zr ratios on the amorphization of ternary Cu-Ni-Zr alloys (initially, Cu-43Ni-7Zr, Cu-12Ni-31Zr, Cu-33Ni-7Zr, and Cu-12Ni-23Zr; and later, Cu-23Ni-15Zr and Cu-11Ni-7Zr). Microstructure was determined using X-Ray diffraction and electron microscopy. Results were compared to thermodynamic models. In the ternary alloys under study, the lattice parameter of the Cu-Ni solid solution was generally correlated to the amounts of nickel incorporated into the Cu lattice. However, longer milling times reduced that lattice parameter and facilitated Zr insertion into the solid solution. For example, after 5 h of milling time, microstructural analysis showed the formation of a solid solution with cubic structure in Cu-43Ni-7Zr. This pattern is consistent with the presence of a lattice parameter between that of Cu and Ni (alpha-phase); in contrast, the Cu-33Ni-7Zr alloy showed an alpha-phase and another similar to Zr. Results suggest that, as the amount of nickel increases, the ability to form an amorphous phase decreases. Additionally, experimental and thermodynamic data showed a solid-solution formation stage, followed by an amorphous phase formation stage that occurred as milling time and Zr content increased. (C) 2018 Published by Elsevier B.V.  
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  Corporate Author Thesis (up)  
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  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0925-8388 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000444341900095 Approved  
  Call Number UAI @ alexi.delcanto @ Serial 1406  
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Author Guzman, D.; Garcia, C.; Soliz, A.; Sepulveda, R.; Aguilar, C.; Rojas, P.; Iturriza, I.; Luno-Bilbao, C. doi  openurl
  Title Synthesis and Electrochemical Properties of Ti-Si Alloys Prepared by Mechanical Alloying and Heat Treatment Type
  Year 2018 Publication Metals Abbreviated Journal Metals  
  Volume 8 Issue 6 Pages 417  
  Keywords POWDERS; ANODES; ELECTRODES; METALS; MICROSTRUCTURE; EVOLUTION; MIXTURES; TITANIUM; SYSTEM; ACID  
  Abstract The aim of this work was to study the synthesis and electrochemical properties of Ti 2 wt %-Si alloys prepared by mechanical alloying (MA) and heat treatment. The MA process was performed under Ar atmosphere. The structural, morphological, and compositional evolutions during the milling and subsequent heat treatment were investigated by X-ray diffraction, energy-dispersive spectroscopy, and scanning electron microscopy. The electrochemical behavior was evaluated by open circuit potential and linear sweep voltammetry measurements. The results showed that the MA process promotes the formation of a supersaturated alpha-Ti-Si solid solution. During heat treatment, the Si remaining in the mechanically alloyed powders and the Si from the alpha-Ti-Si supersaturated solid solution reacted with Ti to form Ti-Si intermetallic compounds. These compounds have a fine and homogeneous distribution in the alpha-Ti matrix, which cannot be achieved by conventional casting methods. Additionally, the electrochemical evaluations revealed that the mechanically alloyed and heat-treated Ti 2 wt %-Si powders have better corrosion resistance in 1.63 M H2SO4 than the pure Ti and MA Ti-Si samples. This is likely due to the particular microstructure produced during the milling and subsequent heat treatment.  
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  Corporate Author Thesis (up)  
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  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2075-4701 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000436115600045 Approved  
  Call Number UAI @ alexi.delcanto @ Serial 1408  
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Author Martinez, C.; Briones, F.; Rojas, P.; Aguilar, C.; Guzman, D.; Ordonez, S. doi  openurl
  Title Microstructural and mechanical characterization of copper, nickel, and Cu-based alloys obtained by mechanical alloying and hot pressing Type
  Year 2017 Publication Materials Letters Abbreviated Journal Mater. Lett.  
  Volume 209 Issue Pages 509-512  
  Keywords BULK METALLIC GLASSES; CORROSION BEHAVIOR; THERMAL-STABILITY; AMORPHOUS-ALLOYS; GRAIN-SIZE; NANOCRYSTALLINE; CRYSTALLINE; HEAT  
  Abstract Mechanical alloying and uniaxial compaction were used to obtain configurations of: elemental powders of Cu and Ni; binary alloys (Cu-Ni and Cu-Zr); and a ternary alloy (Cu-Ni-Zr) under the same mechanical milling and hot pressing conditions. Microstructure and mechanical properties of these were investigated. According to XRD results, hot pressing process increases crystallite size and decreases microstrain in the compact samples, due to the release of crystalline defects without crystallization of amorphous alloys. The milled powder samples have a higher hardness than the unmilled samples, since crystal defects are incorporated into microstructural refinement during milling. The ternary alloy Cu-40Ni-10Zr had the highest hardness of all systems studied, reaching 689 HV0.5. Compression tests at 5% strain determined that Zr-containing samples (amorphous phase) become more fragile after processing, and have the lowest values of compressive strength. In contrast, Ni samples and Cu-Ni binary alloys are more resistant to compression. (  
  Address  
  Corporate Author Thesis (up)  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0167-577X ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000413124300129 Approved  
  Call Number UAI @ alexi.delcanto @ Serial 1409  
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Author Martinez, C.; Briones, F.; Rojas, P.; Ordonez, S.; Aguilar, C.; Guzman, D. doi  openurl
  Title Microstructure and Mechanical Properties of Copper, Nickel and Ternary Alloys Cu-Ni-Zr Obtained by Mechanical Alloying and Hot Pressing Type
  Year 2017 Publication MRS Advances Abbreviated Journal MRS Adv.  
  Volume 2 Issue 50 Pages 2831-2836  
  Keywords BULK METALLIC GLASSES; GRAIN-SIZE; NANOCRYSTALLINE MATERIALS; AMORPHOUS-ALLOYS; PROFILE ANALYSIS; BEHAVIOR; POWDERS; WEAR  
  Abstract Elemental powders of Cu and Ni, binary alloys (Cu-Ni and Cu-Zr) and ternary alloy (Cu-Ni-Zr) obtained by mechanical alloying and uniaxial compaction hot microstructure and mechanical properties were investigated. The alloys studied were: pure Cu, pure Ni, binary alloys (Cu-Ni; Cu-Zr) and ternary alloys (Cu-Ni-Zr) under the same mechanical milling and hot pressing conditions. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM); the mechanical properties were studied by compression tests and hardness in Vickers scale (HV0.5) on polished surfaces at room temperature. According to XRD results, hot pressing process crystallite size increase and microstrain decreases in the compact samples due to the release of crystalline defects. The compacted samples have porosity of approximately 20%. The milling powder samples have a higher hardness than the unmilled samples, this because during milling crystal defects are incorporated together with the microstructural refinement. Ternary alloy is the one with the highest hardness of all systems studied, reaching 689 HV0.5. In compression tests determined a strain 5 %, Zr-containing samples become more fragile presenting the lowest values of compressive strength. In contrast, samples of Ni and Cu-Ni binary alloy are more resistant to compression.  
  Address  
  Corporate Author Thesis (up)  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2059-8521 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000412784800004 Approved  
  Call Number UAI @ alexi.delcanto @ Serial 1410  
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Author Rojas, P.A .; Martinez, C.; Aguilar, C.; Briones, F.; Zelaya, M.E.; Guzman, D. doi  openurl
  Title Characterization of phase changes during fabrication of copper alloys, crystalline and non-crystalline, prepared by mechanical alloying Type
  Year 2016 Publication Ingenieria E Investigacion Abbreviated Journal Ing. Invest.  
  Volume 36 Issue 3 Pages 102-109  
  Keywords EXTENDED SOLID SOLUBILITY; CU-ZR BINARY; NANOCRYSTALLINE METALS; BEHAVIOR; POWDERS; SYSTEM; DISPERSION; GLASS; SIZE; TI  
  Abstract The manufacture of alloys in solid state has many differences with the conventional melting (casting) process. In the case of high energy milling or mechanical alloying, phase transformations of the raw materials are promoted by a large amount of energy that is introduced by impact with the grinding medium; there is no melting, but the microstructural changes go from microstructural refinement to amorphization in solid state. This work studies the behavior of pure metals (Cu and Ni), and different binary alloys (Cu-Ni and Cu-Zr), under the same milling/mechanical alloying conditions. After high-energy milling, X ray diffraction (XRD) patterns were analyzed to determine changes in the lattice parameter and find both microstrain and crystallite sizes, which were first calculated using the Williamson-Hall (W-H) method and then compared with the transmission electron microscope (TEM) images. Calculations showed a relatively appropriate approach to observations with TEM; however, in general, TEM observations detect heterogeneities, which are not considered for the W-H method. As for results, in the set of pure metals, we show that pure nickel undergoes more microstrain deformations, and is more abrasive than copper (and copper alloys). In binary systems, there was a complete solid solution in the Cu-Ni system and a glass-forming ability for the Cu-Zr, as a function of the Zr content. Mathematical methods cannot be applied when the systems have amorphization because there are no equations representing this process during milling. A general conclusion suggests that, under the same milling conditions, results are very different due to the significant impact of the composition: nickel easily forms a solid solution, while with a higher zirconium content there is a higher degree of glass-forming ability.  
  Address  
  Corporate Author Thesis (up)  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0120-5609 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000392963200014 Approved  
  Call Number UAI @ alexi.delcanto @ Serial 1411  
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