Alloy design concept for bcc-T2 silicide-B2 aluminide multicomponent alloys

For the development of refractory metal-based high temperature bcc alloys, the phase equilibrium between bcc (Nb-Mo) and T2 (Nb, Mo)5(Si,B)3 has been investigated. Bcc matrix phase is for toughening at ambient temperatures, and T2 phase is for strengthening and also for oxidation resistance. However, the oxidation resistance of T2 phase is still under investigation. B2-NiAl phase has been utilized as coating materials for Ni-based superalloys for many years. However, addition of Al and transition metal element such as Ni and Fe results in the formation of brittle Laves phases in refractory metal-based bcc alloys. In the present study it is found that additive element selection in terms of atomic size control is effective to avoid the formation of Laves phase. From this phase stability viewpoint, a three-phase alloy composed of Nb, Mo, Si, B, Ni and Al is proposed as a first step for designing three-phase alloys. Please click Additional Files below to see the full abstract

CP asymmetries of B to phi K_S and B to eta' K_S in SUSY GUT Model with Non-universal Sfermion Masses

We analyze CP asymmetries of B \to \phi K_S and B \to \eta' K_S in a supersymmetric grand unified theory in which only the third generation sfermions contained in 10(Q, U^c, E^c) of SU(5) can have a different mass from the others. One of the advantages of this nonuniversal mass model is that the first two generation sfermion masses can be large whereas both (left and right handed) stops are light so as to stabilize the weak scale. Therefore, we studied a minimal supersymmetric standard model parameter region in which a fine tuning in Higgs sector is relaxed owing to light masses of stops, gluino and higgsinos. In such a parameter region, the chargino contribution is as important as the gluino one. We show that the CP asymmetries of B \to \phi K_S and B \to \eta' K_S can deviate from their standard model predicted values by O(0.1) because of constructive interference between gluino and chargino contributions.Comment: 22 pages, 5 figure