[en] Highlights: • New medium-entropy high speed steel coatings exhibit excellent hot wear resistance • Secondary hardening due to coherent nano-sized M₂C contributes to the high hardness • The secondary hardening is enhanced with the increasing C content • The C content needs to be optimized for high hardness and good hot wear resistance Novel Fe₆₈(MoWCrVCoNiAlCu)₃₂ (at.%) medium-entropy high-speed steel (ME-HSS) coatings, containing various carbon contents from 0.65 to 1.05 wt%, are prepared by laser rapid solidification. The newly prepared ME-HSS coatings are characterized by a hard martensitic matrix enhanced by secondary hardening, and specifically by coherent nano-sized M₂C. The secondary hardening effect is enhanced with the increasing carbon content. The high amount of alloying elements in ME-HSS coatings results in excellent oxidative wear resistance, without leading to serious compositional segregation and coarsening of carbides.

[en] An island of isomers have recently been observed on both sides of the N=40 shell below the Ni isotopes. Isomeric states in the 65Fe and 67Fe allow the knowledge of the single particle structure around the νg9/2 shell. Moreover, the excitation energy of the first 2+ and 4+ states in the 68Fe have been established by β-γ correlation. The evolution of the structure of the Fe isotopes going far away from the valley of stability is, for the first time, given for N>40

[en] The in-beam gamma-ray spectroscopy of "6"8Fe is presented with two new observed transitions. The experiments were performed at RIKEN in the frame work of the first Shell Evolution And Search for 2"+ energy At RIBF (SEASTAR) experiment campaign. First, the experimental setup and the data analysis are introduced in details. Afterwards, the experimental method to identify single peaks by comparing with simulation is discussed. The preliminary inclusive cross section and state exclusive cross sections of "6"9Co(p,2p)"6"8Fe are derived and the level scheme of "6"8Fe is built. (author)

[en] Fragments of mass A=68 and 69 are identified for the first time in thermal fission. Their chain production yields and isotopic percentages are evaluated on ²³⁹Pu. The β-decay half-lives of the very neutron-rich isotopes ⁶⁹Co, ⁶⁸Co and ⁶⁸Fe are measured from time correlations between the selected isotopes and the β particles of their decay

[en] Excited states in ^63,65,67Mn were studied via in-beam γ-ray spectroscopy following knockout reactions from ⁶⁸Fe. Similar level schemes, consisting of the 11/2⁻, 9/2⁻, 7/2⁻ and 5/2${}_{g.s.}^{-}$ level sequence, connected by $I\to I-1$ transitions, were established, the first time for ^65,67Mn. Their level structures show features consistent with strongly-coupled rotational bands with $K=5/2$. State-of-the-art shell-model calculations with the modified LNPS effective interaction reproduce the observed levels remarkably well and suggest the dominance of 4-particle-4-hole neutron configurations for all the states. The data on the low-lying excited states of odd-mass ⁵³⁻⁶⁷Mn provide a textbook example of nuclear structure evolution from weak coupling through decoupling to strong coupling along a single isotopic chain on the n-rich side of the β stability line. These results help to deepen our understanding of the $N=40$ “island of inversion”.

[en] The excited states in 63,65,67Mn have been studied via in-beam γ-ray spectroscopy following the knockout reaction of 68Fe by bombarding a liquid hydrogen target. Similar level schemes have been established for the three isotopes, and the level schemes consist of the 11/2-, 9/2-, 7/2- and 5/2-g.s. states, which are connected by Δ I = 1. The level sequences of 65,67Mn show features of strongly coupled rotational band with Kπ = 5/2- expected for the well deformed nuclei. Large-scale shell-model calculations using the modified LNPS (LNPSm) effective interaction reproduce the observed levels remarkably well and suggest the dominance of 4-particle-4-hole (4 p-4 h) neutron configurations and 1-particle-1-hole (1 p-1 h) proton configurations for all the states. The experimental results show an enhancement of Urea neutrino cooling in the accreted neutron crust associated with A=63 nuclei and rule out significant cooling from A = 65, 67. (authors)

[en] The masses of 48 neutron-rich nuclei extending from ⁵⁵Sc to ⁷⁵Cu have been determined from the final set of data to be acquired with the time-of-flight-isochronous (TOFI) spectrometer. The masses of eight isotopes (⁶⁸Fe, ^70,71Co, ⁷³Ni, and ^72endash75Cu) are reported for the first time. The resulting masses now tie in neatly with the masses of previously measured neutron-rich Zn and Ga isotopes determined from fission product β-endpoint measurements. A careful evaluation of the calibration sensitivity is made with respect to inclusion or exclusion of these heavy known species and excellent calibration stability is found. Contrasting these results with previous TOFI measurements, we find that these new results fall between the results of Tu et al. (1) which trend to slightly less bound masses as one proceeds to the most neutron-rich species and Seifert et al. (2) which shows the opposite trend. Good agreement with the predictions of several mass models and Audi-Wapstra systematics are found. copyright 1998 American Institute of Physics

[en] Co and Fe isotopes have been identified in thermal-neutron-induced fission of ²³⁹Pu. The yields of the very neutron-rich isotopes ⁶⁹Co, ⁶⁸Co, and ⁶⁸Fe were measured and their β-decay half-lives were obtained from time correlations between detection of the selected isotopes and of the β particles from their decay

[en] The neutron-rich nuclei ₂₁^57,58Sc, ₂₂^58-60Ti, ₂₃^60-63V, ₂₄^62-66Cr, ₂₅^64-68Mn, ₂₆^67-70Fe and ₂₇^69-71Co have been produced at Ganil via interactions of a 61.8 A.MeV ⁷⁶Ge beam with a ⁵⁸Ni target. Beta-decay studies have been achieved, bringing new half-lives and a better nuclear structure knowledge in this region. These results could help for understanding the over-abundances of the neutron-rich stable ⁵⁸Fe, ⁶⁴Ni in certain inclusions of meteorites. (orig.)

[en] The evolution of nuclear structure in nuclei far from the β stability line is one of the 'hot topics' in modern experimental and theoretical nuclear physics. The present thesis is devoted to the study of structure of neutron-rich nuclei around N=40. The evolution of the neutron g9/2 orbital with increasing number of neutrons is one of the key points defining the structure of these nuclei at low excitation energy. We used for this investigation as experimental tools the magnetic dipole moments measurements and the β decay spectroscopy. For the measurement of the gyromagnetic factor of the 9/2⁺ isomeric state in Fe⁶¹ we have applied the TDPAD method. This method (like most of measurements of nuclear moments) requires an oriented ensemble of nuclei. The orientation of Fe^61m was achieved via the fragmentation of Ni⁶⁴ at 55 MeV/u and the selection of the fragment momentum with the LISE spectrometer at GANIL. The experimental device was specially conceived to preserve the alignment up to the implantation point. The measured value of the g factor was compared with large-scale shell model and Hartree-Fock-Bogoliubov model predictions. The nuclei studied via β decay were produced by the fragmentation of Kr⁸⁶ at 58 MeV/u. For the selection of reaction products we used for the first time the LISE2000 spectrometer and for the detection of γ rays four EXOGAM clover detectors. We measured 5 new lifetimes and 4 lifetimes with a higher precision. From the prompt βγ coincidences we identified new states in the daughter nuclei, as it is the case of the first 2⁺ excited states in Fe⁶⁸ and Ni⁷². The results were compared with the predictions of the large-scale shell model. Other transitions were observed for the first time in βγ decay of Ti⁶⁰, Fe⁷⁰ and Co^71,73. (author)