[en] A process on how to apply new aluminium alloys by thermal spray coating is discussed. Aluminium-based high alloying compositions were selected as coating materials to protect soft substrates against friction, abrasion and others. The beneficial properties of these new alloys are its high hardness and low friction coefficient. The atomic structures of the alloys are either quasi-crystalline and/or crystalline, and in the latter case the structures obtained have a close structural relation with quasi-crystals

[en] Fatigue tests subjected to constant amplitude under the environments of dry air were performed on 5A06-O aluminum alloy, 7A05-T6 aluminum alloy and 5A06-O/7A05-T6 dissimilar aluminum alloy ring welded joints in a new type sandwich high-pressure shell. The fatigue behaviors were analyzed and compared based on the experimental data, and the mechanisms of welding defect impacts on fatigue properties of the welded joints were deduced from fractographic analysis. It is showed that welding defect has a detrimental influence on fatigue properties of the welded joints. The lower stress level can cause the more obvious decrease of fatigue life of the welded joints. Fatigue cracks of aluminum alloys base metal usually initiated at the surface defects such as two-phase particles and inclusions, and however, welding defect of welded joints are more likely to cause stress concentration and lead to the early initiation of fatigue cracks, which is dominated in decreasing of fatigue life of the welded joints. (paper)

[en] Short communication

[en] Continuous and interrupted torsion tests have been conducted in the temperature range of 320-520 deg C at constant strain rates of 1.26-5.71 x 10^-3 sec^-1 on an Al-Cu-Mg alloy. During the continuous deformation, dynamic recrystallization was observed above 370 deg C and the nucleation of the recrystallization at dislocation clusters or adjacent to second phase particle. The presence of deformation substructure in the recrystallized grain provided a direct evidence that recrystallization had occurred during the deformation. In the interrupted tests, duration of the interruptions were 10,20, or 40 sec at equal strain intervals of either 0.4 or 0.6. During the interrupted deformation, the major softening mechanism was static recovery and partially static recrystallization above 370 deg C. The degree of softening was augmented by increase in the temperature, the interruption strain, and the interruption time. (Author)

No abstract available

[en] The Moessbauer spectroscopy was applied to study radiation damage in Al-0.09 m% Fe alloys (having Al₁₃Fe₄ and solid solution phases) irradiated with 225 MeV Ar ions at room temperature. In the Moessbauer spectra of irradiated samples a dose dependent increase of the intensity of line representing iron atoms in solid solution was observed. Simultaneously, the intensity of lines belonging to the iron atoms in Al₁₃Fe₄ phase decreased with increasing fluences. The depth dependence of the irradiation induced phase transformation shows a qualitative agreement with the elastic collision energy transferred to the matrix by the heavy ion. (author) 12 refs., 3 figs

[en] The formability of AA7050 aluminum alloy sheet is characterized under isothermal forming conditions at room temperature and 150 °C. The material was tested in the T6 condition. Nakazima limiting dome height (LDH) tests in conjunction with stereoscopic digital image correlation (DIC) strain measurements are used for the formability assessment. Four-point forming limit curves (FLCs) were developed at the two test temperatures. AA7050-T6 is shown to respond positively to elevated temperature forming with a 0.19 major true limit strain for a 76.2 mm Nakazima specimen, for example, compared to 0.13 at room temperature. The current results for AA7050-T6 are compared to the formability of AA7075-T6 sheet tested under similar conditions; a slightly higher formability was observed for the AA7075-T6 alloy at the elevated temperature. (paper)

[en] Short communication

[en] Three methods available in the literature to estimate the axial S-N curve from the rotating bending fatigue performance were summarized. Axial and rotating bending fatigue tests were conducted at various alternating stresses on specimens excised from A356 aluminum alloy castings in the high cycle fatigue range. These data were used to assess the effectiveness of the models. Among the three models, the one developed by Manson and Muralidharan did not provide good estimates of the axial fatigue performance from rotating bending data. The geometric correction factor proposed by Philipp yielded the best fit, however, did not alter the Basquin exponent whereas the one proposed by Halford and Manson provided a poor estimate. Only the model proposed by Esin provided accurate estimates of fatigue performance as well as the Basquin exponent.

[en] The factors on premature failure of the traditional extrusion die for the big flat tube profiles were introduced. And the characteristics of the conventional structure was analyzed. Through an actual sample, a new type of hollow die structure for these profiles was presented. The composition elements of the new die structure were described. The selection of the main structural parameters was explained, and the characteristics of this new structure was described. In particular, the metal feeding way of this structure can greatly reduce the extrusion force. The new die structure has obvious advantages, which could greatly improve the die life. This is a type of die structure which is worth promoting. (paper)