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Industrial alloyed steels were investigated. Transformations in supercooled austenite upon continuous cooling was analyzed by dilatometry, and thermokinetic diagrams for the studied steels in the cooling rate range from 0.1 to 30°C/s were built based on obtained results. The influence of alloying elements on the stability of supercooled austenite and on the structure formation upon thermal treatment was shown. Statistical analysis of the results allowed finding analytical dependences which relate the chemical composition of the steels with their properties: temperatures of onset of bainite and austenite formation, stability of austenite.

Special features of the transformations of supercooled austenite occurring under continuous cooling of a promising high-strength steel grade not standardized in the Russian Federation are determined. A method for evaluating the volume fractions of structure constituents formed in the steel as a result of cooling from 925°C at various constant rates within 0.025 – 75 K/sec is proposed and tested. The results are generalized in the form of a thermokinetic diagram of transformations of supercooled austenite.

The methods of optical, electron, and atomic force microscopy are used to study the morphology of bainite formed in high-strength structural steel 25G2S2N2MA (HY-TUF) under isothermal quenching. It is shown that the temperature of the transformation affects the substructure of the bainite, which is represented by ordered layers of plates with a width obeying a lognormal distribution law. It is shown that the bainite plates consist of nanosize subplates, the size of which is determined by the temperature of the bainitic transformation.

The MEG II experiment, based at the Paul Scherrer Institut in Switzerland, reports the result of a search for the decay μ + → e + γ from data taken in the first physics run in 2021. No excess of events over the expected background is observed, yielding an upper limit on the branching ratio of B ( μ + → e + γ ) < 7.5 × 10 - 13 (90% CL). The combination of this result and the limit obtained by MEG gives B ( μ + → e + γ ) < 3.1 × 10 - 13 (90% CL), which is the most stringent limit to date. A ten-fold larger sample of data is being collected during the years 2022–2023, and data-taking will continue in the coming years.

The final results of the search for the lepton flavour violating decay μ + → e + γ based on the full dataset collected by the MEG experiment at the Paul Scherrer Institut in the period 2009–2013 and totalling 7.5 × 10 14 stopped muons on target are presented. No significant excess of events is observed in the dataset with respect to the expected background and a new upper limit on the branching ratio of this decay of B ( μ + → e + γ ) < 4.2 × 10 - 13 (90 % confidence level) is established, which represents the most stringent limit on the existence of this decay to date.

A dilatometric study of steel 45Kh5MF used for making rolling mill rolls is performed. The results of the dilatometric and metallographic analyses are used to determine the kinetics of the perlitic transformation in the steel under continuous cooling. The developed method of numerical simulation of structural transformations under continuous cooling is used to solve the inverse problem and to plot a computational isothermal diagram of decomposition of supercooled austenite in steel 45Kh5MF in the range of perlitic transformation. To check the solution obtained an experimental isothermal diagram of decomposition of austenite in steel 45Kh5MF in the perlitic range is plotted. The data of both diagrams match accurately enough.

The MEG II experiment, located at the Paul Scherrer Institut (PSI) in Switzerland, is the successor to the MEG experiment, which completed data taking in 2013. MEG II started fully operational data taking in 2021, with the goal of improving the sensitivity of the μ + → e + γ decay down to ∼ 6 × 10 - 14 almost an order of magnitude better than the current limit. In this paper, we describe the operation and performance of the experiment and give a new estimate of its sensitivity versus data acquisition time.

A new analytical description for the bainitic transformations in steel on isothermal holding is proposed, on the basis of a logistical function of the holding time (in logarithmic form). The model is characterized by the parameters a and b , which are constant in the given experimental conditions (austenitization temperature, isothermal holding temperature and time, chemical composition of the steel, etc.). The calculated temperature dependence of a and b is in good agreement with experimental data. In further research, the physical significance of coefficients a and b in the logistical function should be refined.

Water-drip cooling devices based on centrifugal jet atomizers are studied experimentally. Their main operating characteristics such as the irrigation density, the uniformity of the distribution of irrigation over the cooled surface, the dependence of the heat transfer factor on the surface temperature, etc. are determined. The effect of the design and production parameters of the quenching facilities on their operating characteristics and mode of cooling of large steel articles is considered for mill rollers as an example. The results of the tests are used to design cooling facilities and heat treatment processes for mill rollers with the use of water-drip quenching.

We present the first direct search for lepton flavour violating muon decay mediated by a new light particle X, μ + → e + X , X → γ γ . This search uses a dataset resulting from 7.5 × 10 14 stopped muons collected by the MEG experiment at the Paul Scherrer Institut in the period 2009–2013. No significant excess is found in the mass region 20–45 MeV/c 2 for lifetimes below 40 ps, and we set the most stringent branching ratio upper limits in the mass region of 20–40 MeV/c 2 , down to O ( 10 - 11 ) at 90% confidence level.