Sarkar Sudip Kumar, Shinde Deodatta, Sen Debasis, Biswas Aniruddha
Materials Science Division, Bhabha Atomic Research Centre, Mumbai400085, India.
Homi Bhabha National Institute, Mumbai400094, India.
Microsc Microanal. 2021 Dec 2:1-15. doi: 10.1017/S1431927621013659.
The quantitative characterization of small nano-sized precipitates poses genuine challenges and is often deficient in accuracy due to the inherent limitations inevitably associated with the individual experimental techniques. A convenient solution is to utilize multiple complementary techniques. The present work demonstrates an effective way to reliably quantify nano-sized precipitates using a combination of complementary techniques of atom probe tomography (APT), small angle neutron scattering (SANS), and transmission electron microscopy (TEM). As a case study, the size (radius, r), number density (NP), volume fraction (ϕ), and chemical composition of Cr-rich α′ precipitates are determined in Fe–20 at% Cr alloy, thermally aged at 773 K for 1,000 h. This combinatorial approach utilizes the strength of each technique in such a way that the overall accuracy of quantitative precipitation analysis improves significantly. For example, the superior spatial resolution makes TEM the appropriate technique to estimate the size and size distribution of the precipitates, while APT provides the chemical composition. Similarly, SANS analysis incorporates both the size and the compositional information thus derived independently and provides statiscally averaged quantitative analysis overcoming the field-of-view limitations of both TEM and APT. This combinatorial approach improves the accuracy of quantification and provides the true representation of the microstructure.
对小尺寸纳米析出相进行定量表征面临着诸多实际挑战，并且由于各种实验技术本身不可避免的局限性，其准确性往往不足。一个简便的解决办法是采用多种互补技术。本研究展示了一种有效的方法，即结合原子探针断层扫描（APT）、小角中子散射（SANS）和透射电子显微镜（TEM）等互补技术，来可靠地定量分析纳米析出相。作为一个案例研究，在773 K下热时效1000 h的Fe–20 at% Cr合金中，测定了富Cr的α′析出相的尺寸（半径，r）、数密度（NP）、体积分数（ϕ）和化学成分。这种组合方法利用了每种技术的优势，使得定量析出分析的整体准确性得到显著提高。例如，TEM具有出色的空间分辨率，是估算析出相尺寸和尺寸分布的合适技术，而APT则能提供化学成分信息。同样，SANS分析整合了通过上述两种技术独立获得的尺寸和成分信息，并提供统计平均的定量分析结果，克服了TEM和APT的视场限制。这种组合方法提高了定量分析的准确性，并真实地反映了微观结构。
