HDDR conditions for obtaining the anisotropic Nd-Fe-B powders and their microstructures have been investigated. For both of the disproportionation and recombination stages, the alloys treated at the H₂ pressures which are close to the equilibrium one, result in highly anisotropic powders. Anisotropic volume expansions of the disproportionated alloys were observed, which would be the key to the inducement of anisotropy.

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一般的に，Nd₂Fe₁₄B相とPr₂Fe₁₄B相の結晶化温度(約630 ℃)の同程度の値であることが報告されている。しかしながら，化学量論組成より希土類リッチなNd (or Pr)-Fe-B系磁石膜の結晶化過程においての微細構造制御を通じた保磁力向上の観点より，上記2種類の磁石膜において，最適な熱処理温度（熱処理時間）が異なる事が考えられる。本研究では，PLD法で作製した試料に対し，著しく速い昇温速度を有するパルス熱処理に着目し，Nd-Fe-

，Pr-Fe-B系の各磁石膜における保磁力に対する最適熱処理時間を比較，検討したので報告する。

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The magnetization process of an Nd-Fe-B hydrogenation-disproportionation-desorption-recombination (HDDR) magnet was studied by measuring its initial recoil curves. When compared with those of Nd-Fe-B sintered, HDDR and melt-spun magnets, the behavior of the initial recoil curves of the HDDR magnet was similar to that of the sintered magnet when the applied magnetic field was relatively small. The behavior of the initial recoil curves of the HDDR magnet became similar to that of the melt-spun magnet when the applied field became larger. The magnetic microstructure of the HDDR magnet was observed by means of a magnetic force microscope (MFM). When the HDDR magnet was thermally demagnetized, the distance of two domain walls was smaller than the average grain size of the HDDR magnet. On the other hand, the distance of two domain walls was larger than the average grain size of the HDDR magnet when the magnet was magnetically demagnetized. These results suggest that the HDDR magnet contains a multi-domain structure when the magnet is thermally demagnetized or when the applied field is relatively small. However, the HDDR magnet has only a single-domain structure after the application of sufficiently large fields.

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Recent progress in hydrogenation-decomposition-desorption-recombination (HDDR) process technologies is described with regard to the commercial production of Nd-Fe-B magnet powders. The applications of the powders to resin-bonded magnets and hot-pressed magnets are also presented. The HDDR reaction kinetics is an essential factor for improvements in magnetic properties of the Nd-Fe-B powders. Modified HDDR process, i.e., annealing the decomposed alloys under an Ar atmosphere, and then evacuating them with the correct desorption rate, can enhance magnetic anisotropy and coercivities of the powders simultaneously. Utilizing the rapidly solidified alloy flakes as a starting material of the HDDR process induces higher anisotropy in the final powders than using the conventional book-mold cast ingots. This can be ascribed to the complete elimination of α-Fe before the HDDR process. By these improved process, the following powders can be now commercially produced: high B_r-type with (BH)_max of 302-342 kJ/m³, high H_c-type with H_cJ of 1430-1590 kA/m, and super high B_r-type with (BH)_max of 350-390 kJ/m³. Compression-molded resin-bonded magnets with (BH)_max up to 199 kJ/m³ can be fabricated from the super high B_r-type powders. Fully dense magnets produced by hot pressing the oriented high H_c-type powders exhibit excellent thermal stabilities.

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Nd_12.6-xDy_xFe_bal.Co_yB_6.2Zr_0.1Ga_0.3(x =0.3-1.9, y =5.8-18.3) alloys were processed by improved HDDR process with intermediate argon treatment and desorption under constant H₂ pressure to increase remanence and coercivity, respectively. In this study, we investigated effect of Co and Dy contents on the magnetic properties of the HDDR powders. By the improved process, remanence of HDDR powders containing 0.3 at.% Dy and 12 to 16 at.% Co is increased to a maximum of 0.96 T, and coercivity of them containing 0.9 to 1.6 at.% Dy and 5.8 at.% Co is increased to the maximum of 1570 kA/m. Undecomposed (Nd, Dy)₂(Fe, Co)₁₄B phase remains in HDDR powders including Dy above the critical content expressed by the line drawn from 0.6 at.% Dy and 18.3 at.% Co to 1.9 at.% Dy and 7.8 at.% Co. The magnetic properties of the bonded magnets with density of 6.2 Mg/m³ made from the Nd_12.0Dy_0.6Fe_bal.Co_5.8B_6.2Zr_0.1Ga_0.3 anisotropic HDDR powder areas follows: B_r =0.87 T, H_CJ=1530 kA/m and (BH)_max =137 kJ/m³. Its temperature coefficient of remanence is -0.11%/°C and of coercivity is -0.43 %/°C.

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Fully dense magnets were prepared by hot pressing of the hydrogenation-decomposition-desorption-recombination (HDDR)-processed powders, and they had very fine microstructures. The typical magnetic properties of the HDDR hot pressed magnet with the composition of Nd_13.0Fe_62.9Co_17.4B_6.2Zr_0.1Ga_0.4 were B_r=1.26 T, H_cJ=969 kA/m and (BH)_max=279 kJ/m³. The magnetic properties and the surface morphology of the machined HDDR thin hot pressed magnets were investigated. The performance of the machined thin hot pressed magnets hardly depended on their thickness, and that of high coercivity magnets with the composition of Nd_12.4Dy_0.6Fe_74.5Co_5.8B_6.2Zr_0.1Ga_0.4 is the same because of their fine microstructures. Furthermore, the thin hot pressed magnets hardly depended on damage by surface roughness. We investigated the long-term stabilities. As a result, the total irreversible flux loss of high coercivity hot pressed magnet with the composition of Nd_12.6Dy_0.6Fe_58.8Co₂₀B_6.2Zr_0.1Ga_0.4Al_1.5 at 423 K was -1.3% after 1000 hours. The HDDR hot pressed magnets make it possible to stabilize the magnetic properties of thin Nd-Fe-B magnets because of their very fine microstructure.

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The effect of Ga addition on the enhancement of coercivity in HDDR-treated Nd-Fe-B powders, was investigated. Microstructural observation revealed that Ga addition suppresses grain growth of recombined Nd₂Fe₁₄B during the DR process. Analysis using the microstructural parameters in Kronmmarüllers equation shows that the α _K value of Ga-added samples (0.48) is larger than that of ternary samples (0.12), which suggests that Ga leads to the development of reduced surface anisotropy in the recombined Nd₂Fe₁₄B grains.

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千葉（2箇所）, 東京（2箇所）, 甲府, 大阪（3箇所）, 徳島で採集した個体群と累代飼育している感受性系統（宝塚系）の合計10系統のチャバネゴキブリのジェル・ベイト剤に対する喫食性および抵抗性を評価した. 供試薬剤として, ヒドラメチルノンA剤, 同B剤, フィプロニル剤, インドキサカルブ剤などを用いた. 直径30cmの容器に餌, 水, シェルターを配置し, チャバネゴキブリ10頭（5♂5♀）を放し, 供試薬剤250mgを24時間与え, 喫食量および, 7日間における死亡率の変化を調べた. ヒドラメチルノンA剤では, 7系統中100%致死したものは感受性系統と大阪A系と徳島系のみであった. 東京A系, 千葉A系は喫食量が感受性系統の5～15%に減少して死亡率が低下し, 逆に東京, 甲府系は喫食量が減らなかったが, 死亡率は0%であった. ヒドラメチルノンB剤は, A剤より喫食量が全体的に多かったが, 各系統の抵抗性の特徴は同様であった. フィプロニル剤は最も効果が高い傾向が見られたが, 千葉, 大阪A系, 同C系で喫食量の低下が見られ, 後2者では致死率が100%に達しなかった. またインドキサカルブ剤は, 徳島系では感受性が非常に高かったが, 千葉A系は喫食量が少なく致死率20%となり, 東京A系と同B系では喫食量が多くても効果が遅延した. 各地の個体群は行動的な喫食抵抗性と薬剤原体に対する抵抗性が混在し, 薬剤ごとに異なる様相を呈していた. これらの実態とその対策について考察する.

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Qスイッチアレキサンドライトレーザー治療による太田母斑部皮膚色の変化をビデオマイクロスコープとコンピューターを用いて解析した．10人の患者の治療前，治療後の母斑部と対照部の画像を採取し，画像解析により3種の表色系で両部の色の差異（■）を計測した．その結果，明るさを示す指標である■L*（L*a**），■メラニン指数（紅斑・メラニン指数系），■明度（マンセル系）が照射前後で有意に変動し（p<0.01），臨床的印象・評価と並行した．従って太田母斑のレーザー治療効果を色測定で定量する場合，明るさを表す指標が最も有用であり，客観的・定量的な効果判定に応用しうるものと考えた．

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We investigated influences of original alloy microstructure on magnetic properties of the isotropic HDDR (hydrogenation-decomposition-desorption-recombination)-treated Nd₁₂₆Fe_79.0Co_2.4B_6.0 powder by comparing two types of starting materials, i.e., the strip cast (SC) alloy and the conventional book-mold cast (BMC) alloy. It was found that utilizing the SC alloy can achieve better I-H loop squareness, and consequently higher remanence in the final powder. The powder prepared from the SC alloy exhibits a more uniform grain structure of the recombined Nd₂Fe₁₄B phase, which is thought to be closely related to its good loop squareness. The effect of using the SC alloy is supposed to be attributed to the complete elimination of α-Fe particles before the HDDR treatment.

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ダイヤモンドや立方晶系窒化ホウ素などの高硬度材料は、砥粒や加工部材として切削研磨加工など幅広い分野において利用されている。こうした材料同様に高硬度、そして高融点であり汎用性のある高ホウ化物結晶を作製した。高ホウ化物結晶としてＡｌ_-_Ｍｇ_-_Ｂ１２正二十面体化合物結晶を、アルゴンガス置換雰囲気炉を用いたアルミニウムフラックス法による簡易手法で、１５００℃のアルミニウム融液から作製した。Ａｌ_-_Ｂの二成分系にマグネシウムを添加することによってγ_-_ＡｌＢ１２型結晶(Ａｌ_から_１．４Ｍｇ_から_０．４Ｂ２２)、ＡｌＭｇＢ１４結晶からなる結晶相を作製した。

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塩化亜鉛濃厚水溶液を溶剤とし,アゾビスイソブチロニトリル(A系)および過硫酸カリウム()をそれぞれ開始剤として,アクリロニトリルの均一系溶液重合を行なった。全重合速度Rpと生長の見掛けの活性化エネルギーEaは次式で表わされる。
ここで,AIBNはアゾビスイソブチロニトリル,ANはアクリロニトリルを示す。
紫外吸収スペクトルおよび粘度測定から,生長過程にはアクリロニトリルに対する塩化亜鉛の配位が関係することが予測された。B系の開始機構は,塩化鉄(III),ベンゾキノン添加によって重合が禁止されないことからみて,かなり複雑なものであることが推測される。ある研究が発表されている。

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Al-Mg-B系高ホウ化物を高温のAl融液から合成（Alフラックス法）した．原料の純度は, Al 4N, Mg 4N, B 99.5%であった.過剰量のAlとそれぞれの原料を混合し, アルミナルツボを用いてアルゴンガス雰囲気炉中で溶融した.結晶は高温のアルミニウム融液から冷却しながら成長させた. 1500℃の温度での保持時間は2～3時間であった．合成した結晶は，過剰なアルミを塩酸で溶かすことによって取り除き回収をした．このようにして得られた結晶はAlMgB14, α,γ-AlB12であった．

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The magnetization mechanism of an Nd-Fe-B HDDR magnet was studied by measuring its recoil curves. When compared with those of isotropic Nd-Fe-B sintered, HDDR, and melt-spun magnets, the behavior of the recoil curves of the HDDR magnet was similar to that of the recoil curves of the melt-spun magnet. This means that the isotropic HDDR magnet behaved like single-domain particles. In addition, calculated isotropic recoil curve that assumes only rotation of the magnetization of single-domain particles showed the same tendency as the recoil curves of the HDDR magnet. This result indicates that the recoil curves of an isotropic HDDR magnet were dominated by rotation of the magnetization, and were not significantly influenced by domain wall movement. Moreover, the recoil curve of an anisotropic HDDR magnet behaved similarly to calculated anisotropic recoil curve based on the rotation of the magnetization of single-domain particles with an orientation distribution. This means that the recoil curves of an anisotropic HDDR magnet were also dominated by rotation of the magnetization. These results suggest that the HDDR magnet behaved like single-domain particles in its recoil curves, which were dominated by rotation of the magnetization and were not significantly influenced by domain wall movement.

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