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研究論文

銅を含有するMg–9%Al合金の亜鉛添加による耐食性改善

川畑博之, 瀬口剛

原稿種別: 研究論文
2014 年 64 巻 12 号 p. 623-627
発行日: 2014/12/30
公開日: 2015/01/30

DOIhttps://doi.org/10.2464/jilm.64.623

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The corrosion resistance of Mg–9 mass%Al alloys deteriorates significantly with increasing copper content. It is very important to prevent the deterioration with increasing copper content, because magnesium alloys easily become contaminated with copper in the process of recycling. We found that the corrosion resistance was obviously improved with increasing zinc content in copper-containing Mg–9 mass%Al alloys. In this study, copper intermetallic compounds and magnesium alloys of single phase including aluminum and zinc were produced. Moreover, their electrical characteristics were investigated in order to clarify the mechanism of the improvement of the corrosion resistance due to zinc addition. Adding zinc to copper-rich alloys made copper-based intermetallic compounds from Mg₆Al₇Cu₃ to Mg₃₂ (Al,Zn,Cu) ₄₉, which is the compound based on Mg₃₂ (Al,Zn) ₄₉ and includes copper. The cathodic current density of Mg₃₂ (Al,Zn,Cu) ₄₉ was much smaller than Mg₆Al₇Cu₃. Therefore, the corrosion resistance was obviously improved with increasing zinc content of Mg–9 mass%Al alloys containing copper.

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摩擦粉末焼結法によるオープンセル型ポーラスアルミニウムの作製

半谷禎彦, 石原綾乃, 桑水流理, 吉川暢宏

原稿種別: 研究論文
2014 年 64 巻 12 号 p. 628-632
発行日: 2014/12/30
公開日: 2015/01/30

DOIhttps://doi.org/10.2464/jilm.64.628

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A new friction powder compaction process by the sintering and dissolution process route for fabricating open-cell porous aluminum (Al), which requires no external heat sources except friction heat, was developed. The sintering of the mixture of Al and NaCl powders was conducted only by a rotating tool plunged into the mixture. Namely, the sintering of the mixture was achieved because of the friction heat and pressing load generated by the rotating tool plunged into the mixture. In this study, porous Al with porosities of 60%, 70% and 80% were successfully fabricated. Their pore structures were observed by SEM and X-ray computed tomography (CT), and their mechanical properties were investigated by compression tests. It was found that almost the entire specimen had pore structures similar to the NaCl morphology regardless of the porosity. Plateau stress decreased with increasing porosity indicating strong relationships between them. Porous Al exhibited ductile fracture regardless of its porosity, which is considered to be attributed to the good bonding between Al particles.

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鋳造後圧延したAl–10%Si–0.3%Mg系合金鋳物の時効硬化挙動

才川清二, 森岡竜一, 松田健二, 寺山清志, 池野進

原稿種別: 研究論文
2014 年 64 巻 12 号 p. 633-637
発行日: 2014/12/30
公開日: 2015/01/30

DOIhttps://doi.org/10.2464/jilm.64.633

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The aging behavior after solutionization in Al–10 mass%Si–0.3 mass%Mg alloy cast into permanent mold and then rolled up to 68% was investigated by OM, TEM and micro-vickers hardness measurement. The eutectic silicon particles are partial diffusion and coarsening with spheroidal after solution heat treatment, Mg₂Si crystallized phase was approximately dissolution into the Al matrix. The alloy aged at 423 K was found to produced needle shaped precipitates parallel to [100] in Al matrix, while streaks along the [100] and [010] directions were observed between diffraction spots of the matrix in each SADP. When the alloy aged at 473 K, β″ phase, parallelogram-type and granular precipitates were observed. These precipitates were very similar to observed in 6000 families alloy wrought material. It was estimated another fine precipitates affected precipitation strengthening in the alloy.

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蒸気コーティング法によるマグネシウム合金上への耐食性皮膜の作製

神山直澄, 石崎貴裕

原稿種別: 研究論文
2014 年 64 巻 12 号 p. 638-642
発行日: 2014/12/30
公開日: 2015/01/30

DOIhttps://doi.org/10.2464/jilm.64.638

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Corrosion resistant films were prepared on magnesium alloy AZ31 by steam coating using NaNO₃ aqueous solution as steam source. The chemical and corrosive resistant properties of the films were estimated using XRD, FT-IR, SEM, and electrochemical method. XRD patterns revealed that the film was composed of crystal Mg (OH) ₂ and Mg–Al system layered double hydroxide (LDH), independent of treatment time. The film grew densely and uniformly with an increase in treatment time. Cross sectional SEM images revealed that the deposition rate was 8 μm/h. FT-IR spectra showed that the Mg–Al LDH had carbonate-ions and nitrate-ions in the interlayer. Potentiodynamic polarization curves of the film treated at 433 K for 7 h indicated that the corrosion current density decreased by more than four orders of magnitude as compared to that of the uncoated one. Immersion test in 5 mass% NaCl aqueous solution at 308 K for 168 h revealed that the chemical composition on the surface of the film treated at 433 K for 7 h changed hardly before and after the immersion test. These results indicates that the film coated AZ31 has a superior corrosive resistance.

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解説

アルミニウムによる軽量化と静音化技術

杉本明男

原稿種別: 解説
2014 年 64 巻 12 号 p. 643-648
発行日: 2014/12/30
公開日: 2015/03/30

DOIhttps://doi.org/10.2464/jilm.64.643

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連載講座

異種原子注入

柴山環樹, 渡辺精一

2014 年 64 巻 12 号 p. 654-662
発行日: 2014/12/30
公開日: 2021/06/15

DOIhttps://doi.org/10.2464/jilm.64.654

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