静高压下非晶(Fe0.99,Mo0.01)78Si9B13合金晶化过程的热力学研究

 在600~930 K，常压到7 GPa的范围内，对非晶(Fe_0.99,Mo_0.01)₇₈Si₉B₁₃合金等温等压退火30 min。实验表明：其晶化产物α-Fe(Mo, Si)、Fe₃B和Fe₂B相的析出与所加压力密切相关。压力使非晶(Fe_0.99,Mo_0.01)₇₈Si₉B₁₃合金的晶化温度和亚稳Fe₃B相的析出温度下降，在一定的压力和温度下，亚稳Fe₃B相将向稳定Fe₂B相转变，其转变温度随压力而变化。还对非晶(Fe_0.99,Mo_0.01)₇₈Si₉B₁₃合金的晶化和亚稳Fe₃B到稳定Fe₂B转变的热力学机制进行了讨论，并给出Fe₃B向Fe₂B的相转变方程。     

非晶FeMoSiB合金机械晶化的动力学机制

 研究了非晶(Fe_0.99Mo_0.01)₇₈Si₉B₁₃（FMSB）合金的机械晶化过程和机制,并讨论了局域高压的作用。结果表明：非晶FMSB合金的晶化过程及其产物与球磨强度和球磨时间有密切关系,在低能球磨FMSB非晶过程中,晶化相只有α-Fe(Mo,Si)固溶体,而在高能球磨过程中,除了α-Fe(Mo,Si)固溶体结晶相之外,还分别有(Fe,Mo)₃B和Fe₂B相析出。其晶化机制可归因于由碰撞引起的局域高压和局域高温共同作用的结果。实验结果还表明,机械球磨不仅对非晶FMSB的常压热晶化温度有重要影响,而且对其热晶化结果亦有重要影响。     

Fe78B13Si9、(Fe0.99Mo0.01)78B13Si9非晶合金的激波晶化实验研究

 研究了Fe₇₈B₁₃Si₉、(Fe_0.99Mo_0.01)₇₈B₁₃Si₉非晶合金的激波晶化行为。激波是由氢-氧爆炸产生的。实验结果表明：激波能使非晶合金在微秒时间内晶化,晶化主相为α-Fe基固溶体,次晶化相为Fe₃Si,且观察到α-Fe基因溶体晶格常数变小。用DTA分析进一步证实：激波晶化是比较完全的,晶化相相当稳定。     

Fe40Ni40P12B8非晶合金的冲击晶化实验研究

 本文研究了Fe₄₀Ni₄₀P₁₂B₈非晶合金冲击波加载下的晶化行为，冲击波由二级轻气炮发射的告诉弹丸撞击靶产生。实验结果表明：Fe₄₀Ni₄₀P₁₂B₈非晶合金在冲击波加载下，晶化可在加载时间（微秒量级）内发生；晶化的阈值压力在30~50 GPa之间，相应的冲击温度约为510~800 K，晶化析出相与冲击压力有关，低压下析出相是面心立方γ-(Fe, Ni)固溶体和Fe₃(P_0.37B_0.63)化合物，高压下（大于60 GPa）析出相除了面心立方γ-(Fe, Ni)固溶体和Fe₃(P_0.37B_0.63)化合物之外，还包括(Fe, Ni)₃P化合物。     

非晶Fe78Si9B13合金在高压下的晶化

 本文研究了压力对Fe₇₈Si₉B₁₃非晶合金晶化温度的影响。给出了常压及7.5 GPa压力下的时间－温度－相变图。结果指出：晶化温度不仅与压力的大小有关，而且还与热处理的时间因素有关。此外，高压下bcc-Fe(Si)相结晶区域明显变大。     

高压下Al与Fe-Mo-Si-B合金固态反应形成Al-Fe基玻璃合金的研究

 在4 GPa，700~900 K温度范围内研究了Al与非晶(Fe_0.99, Mo_0.01)₇₈Si₉B₁₃合金的固态反应过程。利用透射电镜、X射线衍射仪和扫描电镜研究了Al与非晶(Fe_0.99, Mo_0.01)₇₈Si₉B₁₃合金界面所形成的扩散层的微观结构。在780~840 K温度范围内形成的扩散层中观察到Al-Fe基玻璃合金，其晶化温度为870 K左右。还对Al-Fe基玻璃合金的形成机理进行了研究。     

非晶La80Al20晶化相的超导电性

 本文把非晶La₈₀Al₂₀在真空中、不同温度及其时间条件下进行退火，以及在6 GPa不同温度退火40 min，并对退火样品的相结构及超导性进行了研究。发现真空中，250 ℃退火的样品晶化成了T>4.2 K、不超导的单相四方La₄Al；300 ℃及450 ℃退火的样品晶化成La₃Al、α-La、β-La及一些未知杂相，这些多相混合物的T_C<6.0 K。在6 GPa 300 ℃及以下温度退火的样品，晶化成单相六角La₄Al，其晶格常数与六角La₃Al的完全相同，这些样品的T_C>5.1 K；6 GPa、350 ℃及以上温度退火的样品，晶化成La₃Al相及新未知相H，新相H的T_C约为6.3 K。     

高压下Zr70Cu30非晶合金的热稳定性和晶化相的变化

 用电阻测量及X射线衍射法研究了非晶Zr₇₀Cu₃₀合金在常压和高压下热稳定性以及晶化相的变化。结果表明压力提高了这种非晶合金的晶化温度并明显地改变了合金中的相平衡关系。在2 GPa压力下，平衡相为Cu₁₀Zr₇和α-Zr的混合物，而常压下为CuZr₂和少量α-Zr的混合物。     

非晶合金Fe73.5Cu1Nb3Si13.5B9的激波晶化及其特征

 研究了非晶合金Fe_73.5Cu₁Nb₃Si_13.5B₉（FINEMET）的激波晶化。与退火晶化比较,激波晶化具有一系列鲜明特征,这些特征是固态下扩散性相变理论难以解释的,有深刻的物理内涵。     

高压下块状Pd40Ni40P20非晶合金的晶化

 本文研究了Pd₄₀Ni₄₀P₂₀块状非晶在4 GPa及常压下的晶化过程。得到了时间-温度转变图。结果表明：高压下样品的晶化温度明显升高，压力对原子的长程扩散及相分离熔体的粘性流动均有抑制作用。在接近熔点进行高压退火时，获得了单相过饱和固溶体。其晶体结构为面心立方。     

静高压下有表面化学反应的非晶合金晶化研究

在静高压3—5GPa,510—660℃温度下,研究了在晶化过程中其表面与Al发生反应的非晶(Fe_0.99,Mo_0.01)₇₈Si₉B₁₃合金的晶化过程。发现在4GPa左右,510—660℃的温度范围内,非晶FMSB晶化为纳米α-Fe(Al)相,在其他压力下,晶化为α-Fe(Mo,Si),(Fe,Mo)₃B或Fe₂B相。利用简单固体模型对其晶化的热力学机制 关键词：     

Crystallization of Fe-B amorphous alloy powders produced by chemical reduction

The crystallization behaviour of the Fe?B amorphous alloy powders prepared by the chemical reduction method has been investigated by Mössbauer spectroscopy. In comparison to amorphous ribbons prepared by melt-spinning, a different crystallization behaviour has been observed. After annealing the amorphous samples entirely crystallized into three crystalline phases: α-Fe, Fe₃B, and Fe₂B. In the case of Fe₈₀B₂₀ amorphous alloy ribbons produced by melt-spinning technique eutectic crystallization is commonly observed and results in the crystalline phases: α-Fe and Fe₃B. This kind of crystallization was not observed in the chemically prepared samples. The metastable tetragonal Fe₃B phase transformed completely into α-Fe and Fe₂B after annealing at 973 K for one hour.     

Short range order of the amorphous Fe−B powders prepared by borohydride reduction

Ultrafine Fe?B amorphous alloy powders were prepared by reducing Fe²⁺ ions using KBH₄ and NaBH₄ in aqueous solution. Adjusting technological factors, the amorphous powders around the composition of Fe₆₅B₃₅ can be easily obtained, but in the vicinity of eutectic point (Fe₈₀B₂₀) a certain amount of α-Fe often appears in the samples. From the Mössbauer spectrum, the crystallization products of the Fe₆₃B₃₇ amorphous powder are α-Fe and Fe₂B phases. The measurement of¹¹B spin echo nuclear magnetic resonance (NMR) at 8K showed that Fe₂B-like and Fe₃B-like short range orders (SRO) exist in the amorphous powder of Fe₇₆B₂₄.     

Structural transformations of Fe81B13Si4C2 amorphous alloy induced by heating

Thermal stability and crystallization of the Fe₈₁B₁₂Si₄C₂ alloy were investigated in the temperature range 25-700 °C by the XRD and Mössbauer analysis. It was shown that on heating the as-prepared amorphous Fe₈₁B₁₂Si₄C₂ alloy undergoes thermal stabilization through a series of structural transformations involving the process of stress-relieving (temperature range 200-400 °C), followed by a loss of ferromagnetic properties (Curie temperature at 420 °C) and finally crystallization (temperature range 450-530 °C). The process of crystallization begins by formation of two crystal phases: Fe₃B and subsequently Fe₂B, as well as a solid solution α-Fe(Si). With increase in annealing temperature, the completely crystallized alloy involved only two phases, Fe₂B and solid solution α-Fe(Si).XRD patterns established a difference in phase composition and size of the formed crystallites during crystallization depending on the side (fishy or shiny) of the ribbon. The first nuclei of the phase α-Fe₃Si were found on the shiny side by XRD after heat treatment even at 200 °C but the same phase on the fishy side of ribbon was noticed after heat treatment at 450 °C. The largest difference between the contact and free surface was found for the Fe₂B phase crystallized by heating at 700 °C, showing the largest size of crystallites of about 130 nm at 700 °C on the free (shiny) surface.     

Progress of laser spectroscopy at the IGISOL

Magnetic interactions and microstructure in the amorphous and nanocrystalline Fe₉₀Zr₇Cu₁B₂ alloy were investigated. These studies were carried out in the temperature range from 140 up to 380 K, using a Mössbauer spectrometer and completely automated set-up for measurements of magnetic properties. It has been found that the Curie temperature and quadrupole splitting decrease after annealing the sample at 573 K for 1 h (invar effect). However, this behaviour is not observed in nanocrystalline samples. In the early stages of crystallization (the volume fraction of the crystalline phase equal to about 0.06) α-Fe grains above the Curie temperature of amorphous matrix may be treated as non-interacting particles. The particle size estimated by Mössbauer spectra and magnetization curve analysis is equal to about 4 nm.