No abstract

A new type of X-ray diffuse scattering has been found in the early stages of decomposition of the hexagonal phase of Mn-44at.% A1. The diffuse scattering is observed mainly within the basal plane of the reciprocal lattice and differs for the 10T/and l l~l points. Theoretical calculations of the X-ray diffuse scattering according to the kinematic scattering theory have been performed for the elastically isotropic and anisotropic cases and for precipitates of various forms and orientations with and without a depleted layer surrounding them. In the latter case, a zero-intensity region near the reciprocal-lattice points occurs. There are cases of good agreement between the experimental results and calculations for the precipitates with a depleted layer.

No abstract

on the occasion of his 80th birthdayThe dependence of the martensitic Mn-Cu alloy deformation on the magnitude and direction of external stress a t constant temperature and a t heating or cooling is measured. An asymmetry of the a-e hysteresis loop a t isothermal deformation is found. An anomalous shape change in opposite directions of differently loaded samples a t different temperatures during heating is observed. X-ray investigations of structural changes at external stress are performed. A relation between thermomechanical features and crystallographic changes is established. &fCCJIeJIOBaHa 3aBHCHMOCTb nel$OpMaUllH MaPTeHCHTIIbIX CSIJIaBOB l\h-Cu OT BeJIllqllHLI H HanpasneHm BHemHHx IiairpcImeHHii srpn IIOCTORHHOI~ TeMnepaType H B npouecce rxarpeea ti oxnaxneam. nplz ~3 0~e p~~s e c~o i i necbopmUmi o6IrapymeHa acHmieTpaR neTaH r~c~epe3lzca a-e. IIpn HarpeBe Ha6nIonanocb aIroMamHoe ll3MeHeHHe @opMbI B TeMiIepaTypax. I I p o~e n e~b~ peHTreHomwHe HccneaosaHmH CTpywypHbIx H3MeHeHHii IIpOTHBOIlOJIOmHbIX IIaIIpaBJIeHHHX pa3JIH9HO IIarpyXeHHblx 06pa3qOB IIpH pa3JIticlHbIX CIIJIaBOB IIOH BO3nefiCTBHeM BHeIIIHHX HaIIpRXeHHii. noKa3aHa CBH3b MeXiEY TephlO-MeXaHHqeCKHMH CBOfiCTBaMlz ll KpHCTaJIJIOrpa~HseCKHMH ti CTpYHTYPHbIMH 1133IeHe-HHRMH.

Positron lifetime measurements were used for studying decomposition during post-quench in situ annealing of binary Al-7.35 at.% Li and ternary Al-7.3 at.% Li-X (X=1.1 at.% Cu, 5.2 at.% Mg or 0.18 at.% Sc) alloys. A typical lifetime of 185+or-5 ps observed in Al-Li is attributed to coherent delta '(Al3Li) particles. In ternary alloys positrons show a strong response to the formation of semicoherent and incoherent phases such as T1(Al2LiCu) and Al2LiMg. Positron trapping in Al-Li-Sc is attributed to composite delta ' (Al3Li)/Al3Sc particles associated with vacancies. Quenched-in vacancies were detected in Al-Li-Sc and Al-Li-Mg but not in Al-Li-Cu and Al-Li.