Soaring upwards

金沢大学理工研究域機械工学系本研究では，高い強度，優れた耐応力緩和特性，適切な導電性を持つ時効硬化型Cu-Ni-Sn合金の作製を目的とした．市販合金と組成がほぼ同じCu-9%Ni-6%Sn，Cu-15%Ni-8%Sn，Cu-21%Ni-5.5%Sn合金，並びに今回提案するCu-9%Ni-9%Sn合金に400℃でピーク時効後圧延し，応力緩和率を向上のため400℃で焼鈍を行った．この加工熱処理は筆者独自のものである．いずれの合金も，市販合金に比べ引張強さは100～200MPaも高く，導電性は同程度であるが，耐応力緩和特性は劣る．Cu-9%Ni-9%Sn合金が強度，耐応力緩和特性，導電性の面で最もバランスが取れている．In this study, we aimed to fabricate an age-hardened Cu-Ni-Sn alloy with a high strength, an excellent stress relaxation resistance and a suitable conductivity. A Cu-9wt%Ni-9wt%Sn alloy with proposed compositions of Ni and Sn, and Cu-9wt%Ni-6wt%Sn, Cu-15wt%Ni-8wt%Sn, and Cu-21wt%Ni-5.5wt%Sn alloys with almost the same compositions of Ni and Sn as commercial Cu-Ni-Sn alloys were first peak-aged at 400°C, then cold-rolled, and finally annealed at 400°C to improve the stress relaxation resistance of the four cold-rolled alloys. This thermomechanical heat treatment is the author\u27s unique method. The four alloys have tensile strengths higher than those of commercially available alloys by about 100 to 200 MPa, and their conductivities are comparable, but their resistances to stress relaxation are smaller. Among the four alloys, the balance of strength, stress relaxation resistance, and conductivity of the Cu-9%Ni-9%Sn alloy is the most excellent.研究課題/領域番号:15K06480, 研究期間(年度):2015-04-01 - 2018-03-3

Efecto de un programa de desarrollo de habilidades sociales sobre el acoso escolar en estudiantes de primer año de secundaria de una institución educativa pública - San Juan de Lurigancho. Lima, 2018

La presente investigación tuvo como objetivo determinar los efecto de un programa de desarrollo de habilidades sociales sobre el acoso escolar en estudiantes de primer año de secundaria de una institución educativa pública - San Juan de Lurigancho. Lima, 2018. Su diseño de estudio fue de tipo cuasi experimental, constituido por dos grupos de control y experimental a quien se realizó un pre y post test. Se utilizó el instrumento Auto Test de Cisneros de Acoso Escolar. La muestra estuvo conformada por 50 estudiantes de primer año de secundaria, 25 en el grupo de control y 25 grupo experimental, sus edades oscilan de 11 a 13 años de edad. En cuanto al resultado del grupo experimental, se utilizó el estadístico no paramétrico Wilconxon, obtuvo una significancia p= 0.016 aceptando la hipótesis del estudio, es decir los efectos del desarrollo del programa disminuye el acoso escolar en los estudiantes de Institución Educativa Pública ya mencionada. En cambio, para el grupo control se utilizó el estadístico paramétrico T- Student donde se obtuvo la significancia p= 0.066, no se encontró un efecto significativo en el mencionado grupo

Coarsening of δ-Ni2Si precipitates in a Cu-Ni-Si alloy

金沢大学理工研究域機械工学系The coarsening behavior of rod-shaped and spherical δ-Ni 2Si precipitates in a Cu-1.86 wt% Ni-0.45 wt% Si alloy during aging at 823-948 K has been investigated by measuring both precipitate size by transmission electron microscopy (TEM) and solute concentration in the Cu matrix by electrical resistivity. The rod-shaped δ precipitates have an elongated shape along 〈5̄58〉m and a {110}m habit-plane facet. The coarsening theory of a spherical precipitate in a ternary alloy developed by Kuehmann and Voorhees (KV) has been modified to a case of rod-shaped precipitates. The coarsening kinetics of average size of the rod-shaped and spherical δ precipitates with aging time t obey the t 1/3 time law, as predicted by the modified KV theory. The kinetics of depletion of the supersaturation with t are coincident with the predicted t -1/3 time law. Application of the modified KV theory has enabled calculation of the energies of sphere, {110}m and rod-end interfaces from the data on coarsening alone. The energy of the {110}m interface having a high degree of coherency to the Cu matrix is estimated to be 0.4 J m-2, the incoherent sphere-interface energy 0.6 J m-2, and the rod-end interface energy 5.2 J m-2. © 2011 Springer Science+Business Media, LLC

Fatigue behavior and microstructure of an Al-Mg-Sc alloy at an elevated temperature

金沢大学理工研究域機械工学系Al-Mg-Sc alloy polycrystals bearing Al3Sc particles with different sizes, i.e. 4, 6 and 11 nm in diameter, have been cyclically deformed at 423 K under constant plastic-strain amplitudes, and the microstructural evolution has been investigated in relation to the stress-strain response. Cyclic softening after initial hardening is found in specimens with small particles of 4 and 6 nm, but no cyclic softening takes place in specimens with larger particles of 11 nm. These features of cyclic deformation behavior are similar to the results previously obtained at room temperature. Transmission electron microscopy observations reveal that dislocations are uniformly distributed under all applied strain amplitudes in the specimens containing large particles of 11 nm, whereas slip bands are formed in the cyclically softened specimens bearing smaller particles. The cyclic softening is explained by a loss of particle strength through particle shearing within strongly strained slip bands. The 6 and 11 nm Al3Sc particles have a stronger retardation effect on the formation of fatigue-induced stable dislocation structure than 4 nm particles at 423 K. © 2010 IOP Publishing Ltd

Effects of microstructures on fatigue behavior of an Al-Mg-Sc alloy at an elevated temperature

Polycrystalline Al-1wt%Mg-0.27wt%Sc alloys bearing Al3Sc particles with different average sizes of 4 and 11nm Polycrystalline Al-1wt%Mg-0.27wt%Sc alloys bearing Al3Sc particles with different average sizes of 4 and 11nm in diameter have been cyclically deformed at 423K under various constant stress amplitudes, and the relationship between fatigue characteristics and microstructure of the alloy has been investigated. The specimen bearing 11 nm particles exhibited a cyclic hardening to saturation, while in specimens with the small particles a cyclic softening was observed after initial hardening. In the specimen with large particles, dislocations were uniformly distributed under all applied stress amplitudes, whereas the specimens bearing small particles, in which cyclic softening occurred exhibited clearly developed slip bands. The cyclic softening for the latter specimen was explained by particle shearing within the strongly strained slip bands. The width of precipitate free zones (PFZs) has been found to be one of the factors affecting the fatigue life of the specimens at 423K. The two-step aging decreases the width of PFZs, resulting in increase in the fatigue life. © 2012 Trans Tech Publications, Switzerland