1-甲氧基-N-(芳甲叉基)-1-丙胺的质谱解析

讨论了１－甲氧基－Ｎ－（芳甲叉基）－１－丙胺类化合物的质谱，分析了主要碎片离子的产生过程，推测了该类化合物的裂分规律。

Microstructure and mechanical properties of TC4 titanium alloy K-TIG welded joints

The 12 mm-thick Ti−6Al−4V(TC4)titanium alloy plates were welded using keyhole tungsten inert gas(K-TIG)welding at various heat inputs.The microstructure,grain boundary(GB)characteristics and mechanical properties of the weld metal zone(WMZ)were analyzed.The test results show that the K-TIG welds are well formed,and no obvious defects are observed when the heat input is 2.30−2.62 kJ/mm.When the heat input gradually increases,αlaths increase in length,andα′phase and residualβphase are reduced.The electron backscatter diffraction(EBSD)test results indicate that the high-angle GB proportion in the WMZ increases with the increase of heat input.The tensile strength of the WMZ gradually decreases and the elongation of the WMZ increases when the heat input increases from 2.30 to 2.62 kJ/mm.The impact toughness of the WMZ increases as the heat input increases.

光引发剂BDMB的光化性和用途

简要介绍了新型α－断裂光引发剂BDMB的有关物理和化学性质，并介绍了它的用途及应用研究情况。

Effect ofαphase morphology on fatigue crack growth behavior of Ti−5Al−5Mo−5V−1Cr−1Fe alloy

Taking a Ti−5Al−5Mo−5V−1Cr−1Fe alloy as exemplary case,the fatigue crack growth sensitivity and fracture features with various tailoredαphase morphologies were thoroughly investigated using fatigue crack growth rate(FCGR)test,optical microscopy(OM)and scanning electron microscopy(SEM).The tailored microstructures by heat treatments include the fine and coarse secondaryαphase,as well as the widmanstatten and basket weave features.The sample with coarse secondaryαphase exhibits better comprehensive properties of good crack propagation resistance(with long Paris regime ranging from 15 to 60 MPa·m1/2),high yield strength(1113 MPa)and ultimate strength(1150 MPa),and good elongation(11.6%).The good crack propagation resistance can be attributed to crack deflection,long secondary crack,and tortuous crack path induced by coarse secondaryαphase.

Microstructure evolution and mechanical properties of heat treated LCB titanium alloy

The influence of ageing time on microstructure and mechanical properties of low-cost beta （LCB） titanium alloy with a chemical composition of Ti-6.6Mo-4.5Fe-1.5Al was investigated. The correlation between microstructure and fatigue crack initiation and growth was also studied. Increasing ageing time tended to increase the volume fraction of the secondary α-precipitates, β-grain size and partial spheroidization of primary α-phase. The maximum tensile strength （1565 MPa） and fatigue limit （750 MPa） were obtained for the samples aged at 500 °C for 0.5 h, while the minimum ones of 1515 MPa and 625 MPa, respectively, were reported for the samples aged at 500 °C for 4 h. The samples aged at 500 °C for 4 h showed a transgranular fracture mode. However, the samples aged at 500 °C for 0.5 h revealed a mixture fracture mode of transgranular and intergranular. The formed cracks on the outer surface of the fatigue samples were found to propagate through the β-grains connecting the primary α-particles existing at the β-grain boundaries.

Effect of solid particle erosion on fracture strength of low density polyethylene film

In this study,the infuence of solid particle erosion on the fracture strength of low density polyethylene(LDPE)film under con-trolled conditions is investigated through impact experiments.The variations in the residual fracture stress as well as the residual fracture strain of the LDPE flm after solid particle impact against the impact angle(α),impact velocity(νp)and impact duration(t)are analysed.The study revealed that the fracture stress and the fracture strain of the LDPE film decrease with an increase in the impact duration,and the degradation rate increases with the impact velocity and impact angle.Furthermore,the fracture stress and the fracture strain of LDPE film decrease exponentially against the impact energy under the same particle impact angle condition,and the reductions of fracture stress and fracture strain increase quasi-linearly with the sine-squared impact angle under the same impact energy.The study proposes empirical models to predict the attenuation of the fracture stress and the fracture strain of LDPE films due to the finite particle impact energy.