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

后向散射铁穆斯堡尔探测器主要用于钢结构、墙体、船舶等大型构件的原位无损检测。该探测器可以同时计数内部转换电子、后向散射x射线和伽马射线，并测量所谓的后向散射穆斯堡尔谱，该谱可以指示钢和含铁材料的微观结构变化。利用该探测器，利用转换电子、x射线和伽玛射线获得的反向散射穆斯堡尔谱，研究了双相不锈钢的显微组织变化。商业双相不锈钢通常采用连铸技术制造，由顺磁性奥氏体和铁磁性铁素体相组成。^<57>从双相不锈钢得到的铁穆斯堡尔光谱由两部分组成。一个是从顺磁性奥氏体上升的单共振线的主要组成部分，另一个是从铁磁性铁氧体上升的磁分裂六重奏的次要组成部分。副晶奥氏体具有面心立方（fcc）结构，在高温退火下具有相当稳定的热处理性能，而铁磁铁氧体具有体心立方（bcc）结构，在适当温度下退火后表现为相分解。目前的穆斯堡尔研究清楚地表明，双相不锈钢的铁素体在较低温度（723 k ^<57>）下退火时发生了相分解，铁素体的铁穆斯堡尔谱显示平均超细磁场的大小发生了变化，表明退火后铁素体中的Cr浓度发生了变化。

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.