An End-to-End Computer Vision Methodology for Quantitative Metallography

Metallography is crucial for a proper assessment of material's properties. It involves mainly the investigation of spatial distribution of grains and the occurrence and characteristics of inclusions or precipitates.This work presents an holistic artificial intelligence model for Anomaly Detection that automatically quantifies the degree of anomaly of impurities in alloys. We suggest the following examination process: (1) Deep semantic segmentation is performed on the inclusions (based on a suitable metallographic database of alloys and corresponding tags of inclusions), producing inclusions masks that are saved into a separated database. (2) Deep image inpainting is performed to fill the removed inclusions parts, resulting in 'clean' metallographic images, which contain the background of grains. (3) Grains' boundaries are marked using deep semantic segmentation (based on another metallographic database of alloys), producing boundaries that are ready for further inspection on the distribution of grains' size. (4) Deep anomaly detection and pattern recognition is performed on the inclusions masks to determine spatial, shape and area anomaly detection of the inclusions. Finally, the system recommends to an expert on areas of interests for further examination. The performance of the model is presented and analyzed based on few representative cases. Although the models presented here were developed for metallography analysis, most of them can be generalized to a wider set of problems in which anomaly detection of geometrical objects is desired. All models as well as the data-sets that were created for this work, are publicly available at https://github.com/MLography/MLography.

Phase composition and concentration of yttriumin films during the deposition of aluminumand aluminum alloys from the gas phase

The work is devoted to the study of the stabilizing effect of yttrium additions during the deposition of thin aluminum films, which are used for the manufacture of elements of micro- and nanoelectronic devices. The surfaces of Al films doped with aluminum oxide were investigated using a scanning electron microscope before and after annealing for 300420 s at a temperature of 500 C. It is shown that fine alumina particles are uniformly distributed on the surface of the films during thermal evaporation of a wire made of an Al Al2O3 alloy. By the method of quantitative metallography, the content of the AlxOy phase in the Al films was determined: when spraying wire from the Al Al2O3 alloy, its content was 1012% of the mass fraction; when spraying wire made of Al Al2O3 alloy and Al wire in a ratio of 50:50 1% mass fraction.

Application of Mathematical and Experimental Approach in Description of Sedimentation of Powder Fillers in Epoxy Resin

In this paper, sedimentation inhibition attempts were examined using colloidal silica in a mathematical and experimental approach. Experimental results were validated by a two-step verification process. It was demonstrated that application of quantitative metallography and hardness measurements in three different regions of samples allows us to describe the sedimentation process using modified Stokes law. Moreover, proper application of Stokes law allows one to determine the optimal colloidal silica amount, considering characteristics of applied filler (alumina or graphite). The results of mathematical calculations have been confirmed experimentally—the experimental results show good agreement with the calculated data.

The The effect of iron on precipitation hardening in the Cu-Ni-Mn alloys

The peculiarities in the structure and properties formation of precipitation-hardened Сu–Ni–Mn–Fe alloys within the concentration range of Ni (19.3–21.0 %), Mn (19.5–20.5 %), Fe (0.6–2.7 %), Cu – balance (in wt. %) were investigated in this work. The methods of quantitative metallography, X-ray analysis, scanning electron microscopy, energy-dispersive spectroscopy and differential thermal analysis were applied. Two solid solutions based on a-Cu differing in composition and hardness were found in the structure of the cast Сu–Ni–Mn–Fe alloys. The temperature ranges of solutions’ formation were determined as (1010±10) °С and (890±10) °С, correspondingly. NiMn phase was also formed at (405±15) °С due to precipitation hardening. In the Сu–Ni–Mn–Fe alloys annealed at 500 and 900 °С for 60–750 hours, the volume fraction and size of NiMn precipitates increased with prolonging annealing time and lowering annealing temperature. As iron content was raised up to 2.7 wt. %, the density of NiMn precipitates increased, especially during first 60 hours of annealing at 900 °С. By adding iron, oxidation resistance was improved, but melting temperature and fluidity did not yield any significant change. Hardness of the Сu–Ni–Mn–Fe alloys with higher iron contents increased by 10 НRB on average. However, when test temperature was raised up to 400 °С, tensile strength decreased (by ~1.3 times) and elongation dropped markedly (by ~10 times).

Solubility of Cu, Ni, Mn in Boron-Rich Fe-B-C Alloys

In the present study, the microstructure development and mechanical properties of the cast boron-rich Fe–B–C alloys cooled at 10 and 103 K/s were investigated as functions of alloying elements additions. These alloys were prepared in the following compositional ranges: B (10–14 wt.%), C (0.1–1.2 wt.%), M (5 wt.%), where M – Cu, Ni or Mn, balance Fe. Structural properties were characterized by quantitative metallography, X-Ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. Mechanical properties of the structural constituents, such as microhardness and fracture toughness, were measured by a Vickers indenter. Copper becomes negligibly incorporated into the phases Fe(B,C) and Fe2(B,C) of the Fe–B–C alloys, but solubility limit forces the remaining solute into the residual liquid. As a result, the globular Cu inclusions are seen in the structure. As compared with copper, nickel has higher solubility in the constituent phases, with preferential solubility observed in the Fe2(B,C) crystals, where Ni occupies Fe positions. Having limited solubility, nickel also forms secondary Ni4B3 phase at the Fe2(B,C) boundaries. Manganese was found to dissolve completely in the Fe–B–C alloys forming substitutional solid solutions preferentially with Fe(B,C) dendrites. By entering into the iron borides structure, Mn and Ni improve their ductility but lower microhardness. The peculiarities in the structure formation and properties of the doped boron-rich Fe–B–C alloys were explained with electronic structure of the alloying elements considered.

The Role of Microstructure on Tensile Plastic Behavior of Ductile Iron GJS 400 Produced through Different Cooling Rates, Part I: Microstructure

A series of samples made of ductile iron GJS 400 was cast with different cooling rates, and their microstructural features were investigated. Quantitative metallography analyses compliant with ASTM E2567-16a and ASTM E112-13 standards were performed in order to describe graphite nodules and ferritic grains. The occurrence of pearlite was associated to segregations described through Energy Dispersive X-ray Spectroscopy (EDS) analyses. Results were related to cooling rates, which were simulated through MAGMASOFT software. This microstructural characterization, which provides the basis for the description and modeling of the tensile properties of GJS 400 alloy, subject of a second part of this investigation, highlights that higher cooling rates refines microstructural features, such as graphite nodule count and average ferritic grain size.

Modern metallography – the basis of foundry material science

The article briefly discusses the capebilities of modern metallography – optical contrasting, quantitative metallography, image processing programs. The question of the absence of modern literature on metallography is touched on. The problem of representing the structures of materials and the Internet is discussed. The problems of the development of metallographic research in Belarus are also presented. It is noted that the development of metallographic research in Belarus is hampered by the lack of funds for the acquisition of the equipment, as well as the lack of qualified personnel.

The Quality Assurance of Cast and Wrought Aero Jet Engine Components Made from Ni-base Superalloys with Using of Quantitative Metallography Methods and Alloys Lifetime Prediction

The Ni-base superalloys are used in the aircraft industry for the production of aero engine most stressed parts, turbine blades or turbine discs. Quality of aero jet engine components has a significant influence on the overall lifetime of a jet engine as itself as well as the whole airplane. From this reason a dendrite arm spacing, grain size, morphology, number and value of γ′-phase are very important structural characteristics for blade or discs lifetime prediction. The methods of quantitative metallography are very often used for evaluation of structural characteristics mentioned above. The high-temperature effect on structural characteristics and application of quantitative methods evaluation are presented in this paper. The two different groups of Ni-base alloys have been used as experimental material: cast alloys ZhS6K and IN713LC, which are used for small turbine blades production and wrought alloys EI 698VD and EI 929, which are used for turbine disc production. Selected alloys have been evaluated in the starting stage and after applied heat-treatment at 850°C for 24 hrs. This applied heat-treatment causes structural changes in all alloys groups. In cast alloy dendritic structure is degraded and gamma prime average size has grown what has a negative influence on turbine blade creep rupture life. Wrought alloys show partially grain boundary melting and grain size changed due to recrystallization what causes mechanical properties decreasing – ultimate tensile strength mainly.