Development and Application of the simultanious electron, X-ray and gamma-ray Mossbauer Detector

背向散射铁穆斯堡尔探测器是为钢结构墙体、船舶等大型构件的原位无损检测而研制的。该探测器可以同时对内转换电子、背向散射X射线和伽马射线进行计数，并测量出反映钢和含铁材料微观结构变化的所谓背向散射穆斯堡尔谱。利用该探测器，用转换电子、X射线和伽马射线获得的巴克散射穆斯堡尔谱研究了双相不锈钢的微观结构变化。商业双相不锈钢通常是通过连铸技术生产的，由顺磁奥氏体相和铁磁铁素体相组成。从双相不锈钢获得的^&lt；57&gt；Fe穆斯堡尔谱由两个组分组成。一个是顺磁奥氏体单共振线的主要成分，另一个是铁磁性铁氧体产生的磁性分裂六重态的次要成分。铁磁铁氧体具有体心立方(Bcc)结构，在合适的温度下热处理时会发生相分解。穆斯堡尔谱研究清楚地表明，双相不锈钢的铁素体在较低的温度下，如723K，57&GT；Fe的穆斯堡尔谱显示，平均超精细磁场的大小发生了变化，表明退火改变了铁素体中的铬含量。

Backscattering Fe Mossbauer detector has been developed for the use in in-situ non-destructive testing of the large scale component like steel building wall, ships and so on. This detector can make possible to count the internal conversion electrons, backscattered X-ray and gamma-ray, simultaniously and measure the so called backscattering Mossbauer spectrum which can indicate the change in microscopic structure of steels and materials containing iron. Using this detector, the microstructural change in duplex-stainless-steel has been investigated by the bacscattering Mssbauer spectra obtained by the conversion electron, X-ray and gamma-ray. Commercial duplex-stainless-steel has usually been manufactured by a continuous casting technique and consists of a paramagnetic austenite and a ferromagnetic ferrite phase. ^<57>Fe Mossbauer spectra obtained from the duplex-stainless-steel consist of two components. One is a predominant component of the single resonance line rising from a paramagnetic austenite and the other is a minor component of a magnetically split sextet rising from ferromagnetic ferrite. Paramgentic austenite has a face-centered cubic (fcc) structure and a quite stable for heat treatments by annealing at elevated temperatures, but ferromagnetic ferrite has a body-centered cubic (bcc) structure and shows a phase decomposition by annealing at appropriate temperatures. Present Mossbauer study shows clearly that a phase decomposition occurred in ferrite of duplex-stainless steel by annealing at rather low temperature like 723 K.^<57>Fe Mossbauer spectra from ferrite show a change in magnitude of the averaged hyperfine magnetic fields suggesting a change in Cr concentration in ferrite by annealing.