Microstructure and Mechanical Properties of Al-11.3Zn-3.2Mg-1.3Cu-0.2Zr-0.1Sr-x Ti Extruded Aluminum Alloy with Different Aging Process

The influences of adding different amount of Ti(0%,0.39%,0.87%)and three kinds of difierent aging processes(T6,T6I6,RRA)on the microstructure and properties of Al-11.3Zn-3.2Mg-1.3Cu-0.2Zr-0.1Sr were investigated.Results show that an appropriate amount of Ti can effectively inhibit grain growth and thus achieve the efiect of grain refinement.The contribution of dislocation density and dislocation strengthening become the biggest when Ti content is 0.39%.At the same time,the intergranular corrosion depth is the lowest when Ti content is 0.39%.Among the three aging processes,the alloys reach the greatest hardness and tensile strength in T6I6.The biggest tensile strength reaches 716.77 MPa.However,when aging at RRA,the alloys obtain the greatest elongation,reaching 7.2%,as well as the good corrosion resistance.

Effect of Ti content on microstructures and mechanical properties of cast Al-2Li-2Cu-0.5Mg alloy

Ti is regarded as one of the promising grain refiners in cast Al-Li-Cu alloys,but few research works have been done on its independent role.In this study,the effect of Ti on the microstructure evolution and mechanical properties of cast Al-2Li-2Cu-0.5Mg base alloy was investigated.The results revealed that the grains can be prominently refined with the increase of Ti addition.After adding Ti,high density TiB_(2)-Al_(3)Ti composite particles with a low lattice misfit form as heterogeneous nucleation sites for the α-Al matrix.δ’(Al3Li) and T_(1)(Al_(2)CuLi) precipitates that provide enhanced strength are dominated in the alloys after T6 aging treatment.The average size of both δ’ and half-width of δ’-precipitation free zone(PFZ) decreases gradually with the increase of Ti content.This is because the higher binding energy between Ti atoms and vacancies limits the diffusion efficiency of Li atoms,and thus results in a higher ductility.Additionally,no nano-sized Al_(3)Ti or core-shell structure of Al_(3)(Li,Ti) particles are found.The tensile property test results indicate that the Al-2Li-2Cu-0.5Mg alloy achieves optimal properties after aging at 175 °C for 32 h when 0.15wt.% Ti is added.It exhibits a yield strength of 352±5 MPa,an ultimate tensile strength of 423±6 MPa,and an elongation of(3±0.4)%.These findings are expected to offer a reliable theoretical guidance for the industrial composition design of the Al-Li-Cu series cast alloys.

The Effect of Al^(3+), Na^+, NH_4^+ on Ti Content in the Preparation of Ti-ZSM-5

The effect of Al3+, NH, Na+ on the Ti content in the preparation of Ti-ZSM-5 by the isomorphous substitution of ZSM-5 using gaseous TiCl4 as titanium resource has been investigated. It is surprisingly found that although the direct ratio exists between the Ti content and the content of the skeletal Al: y=0.08x2+0.57x+1.23(here y represents TiO2% and x represents Al2O3%). but the catalytic activities of Ti-ZSM-5 for the oxidation of styrene sharply rise with the decrease of TiO2%. The skeletal Al hinders the Ti incorporation into the framework of molecular sieves characterized by FT-IR technique. At the same . NH ion has no effect on the Ti incorporation. but Na+ ion does.

Electron microprobe analysis of Hf and Ti in ultrahigh temperature zircon:Optimized approaches and perspectives

Zircon as a multi-objective typomorphic mineral commonly contains diverse trace elements with specific petrogenetic significances.The Hf abundance in zircon is sensitively indicative of melt fractionation during zircon growth on one hand,and on another,the Ti content is a robust temperature sensor of zircon crystallization and has been effectively u tilized in thermometric estimation.A Hf-Ti negative correlation was previously reported in igneous zircons,and thus a potential Hf thermometry was then speculated.In this work,we performed reliable electron microprobe(EMP)measurements of Hf and Ti in ultrahigh temperature(UHT)zircons from the North China Craton,in optimizing point,line and grid analysis.The EMP contents of Hf and Ti both show a wide range of fluctuation owing to the smaller probe spot,and some of them are higher than the LAICPMS data.The Hf-Ti correlation in UHT zircons displays dual and thus complicated patterns in contrast with the previous consideration,which implicates some other factors controlling the geochemical behaviors of Hf and Ti in zircons.Generally,the estimated Ti temperatures based on the EMP analyses are obviously higher than the LA-ICPMS outcomes,but are well consistent with the actual peak condition of the parent rock.It explains the common underestimation of Ti temperatures in hightemperature metamorphic rocks,by using LA-ICPMS analyses.

Revised Ti-in-biotite geothermometer for ilmeniteor rutile-bearing crustal metapelites

In the present study, the Ti-in-biotite geother- mometer was revised using more than 300 natural rutile- or ilmenite-bearing metapelites collected worldwide. The formulation was empirically calibrated as ln[T（℃）]= 6.313 ＋0.22 41n（XTi ） -0.2881n（XFe ） -0. 4491n（XMg） ＋ 0.15P （GPa）, with Xj=j/（Fe＋Mg＋Al^Ⅵ＋Ti） in biotite, assuming ferric iron content of 11.6 mol% of the total iron in biotite. This thermometer is consistent with the well-calibrated garnet-biotite thermometer within error of i50 ℃ for most of the calibrant samples and can successfully distin- guish systematic temperature changes of different meta- morphic zones in both prograde and inverted metamorphic terranes as well as thermal contact aureoles. Thus, the thermometer truthfully reflects real geologic conditions and can be applied to TiO2-saturated metapelites metamor- phosed at the crustal level within the calibration ranges （450-840 ℃, 0.1-1.9 GPa, XTi = 0.02-0.14 in biotite）.

Investigation on Metallurgical Factors Controlling Charpy Impact Toughness in 1Cr21Ni5Ti Duplex Stainless Steel

Based on the fact that toughness degradation occurred in 1Cr21Ni5Ti duplex stainless steel during slow cooling in a temperature interval of 400-600 ℃ following brazed welding, a simulated embrittlement treatment was utilized to evaluate its emhrittlement tendency. Accumulated experiences have shown that high Ti and A1 contents led frequently to severe toughness deterioration. To elucidate this phenomenon, four heats with various Ti and Al contents were prepared in laboratory-scale melts, which were used to investigate the inherent embrittlement nature. The results have shown that 550 ℃ aging led only to a modest toughness reduction, whereas, aging around 475 ℃ resulted in ferrite embrittlement, regardless of Ti, A1 levels. However, high Ti, A1 levels reduced the austenite phase, which, in the case of its inferior shape and distribution due to insufficient hot deformation, failed to resist cleavagetype cracks initiated in the ferrite phase. Increasing hot-forged areas reduction could modify the shape and distribution of austenite, resulting in the enhanced resistance of the austenite to the cleavage-type cracks, which have been confirmed to be beneficial for brittlement suppression of 1Cr21Ni5Ti duplex stainless steel.