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The relationship between heat-treatment parameters and microstructure in titanium alloys has so far been mainly studied empirically, using characterization techniques such as microscopy. Calculation and modeling of the kinetics of phase transformation have not yet been widely used for these alloys. Differential scanning calorimetry (DSC) has been widely used for the study of a variety of phase transformations. There has been much work done on the calculation and modeling of the kinetics of phase transformations for different systems based on the results from DSC study. In the present work, the kinetics of the ␤ ⇒ ␣ transformation in a Ti-6Al-4V titanium alloy were studied using DSC, at continuous cooling conditions with constant cooling rates of 5 ЊC, 10 ЊC, 20 ЊC, 30 ЊC, 40 ЊC, and 50 ЊC/min. The results from calorimetry were then used to trace and model the transformation kinetics in continuous cooling conditions. Based on suitably interpreted DSC results, continuous cooling-transformation (CCT) diagrams were calculated with lines of isotransformed fraction. The kinetics of transformation were modeled using the Johnson-Mehl-Avrami (JMA) theory and by applying the "concept of additivity." The JMA kinetic parameters were derived. Good agreement between the calculated and experimental transformed fractions is demonstrated. Using the derived kinetic parameters, the ␤ ⇒ ␣ transformation in a Ti-6Al-4V alloy can be described for any cooling path and condition. An interpretation of the results from the point of view of activation energy for nucleation is also presented.

Li‐dendrite growth and unsatisfactory sulfur cathode performance are two core problems that restrict the practical applications of lithium–sulfur batteries (LSBs). Here, an all‐in‐one design concept for a Janus separator, enabled by the interfacial engineering strategy, is proposed to improve the performance of LSBs. At the interface of the anode/separator, the thin functionalized composite layer contains high‐elastic‐modulus and high‐thermal‐conductivity boron nitride nanosheets and oxygen‐group‐grafted cellulose nanofibers (BNNs@CNFs), by which the formation of “hot spots” can be effectively avoid, the Li‐ion flux homogenized, and dendrite growth suppressed. Meanwhile, at the interface between the separator and the cathode, the homogenously exposed single‐atom Ru on the surface of reduced graphene oxide (rGO@Ru SAs) can “trap” polysulfides and reduce the activation energy to boost their conversion kinetics. Consequently, the LSBs show a high capacity of 460 mAh g–1 at 5C and ultrastable cycling performance with an ultralow capacity decay rate of 0.046% per cycle over 800 cycles. To further demonstrate the practical prospect of the Janus separator, a lithium–sulfur pouch cell using the Janus separator delivers a cell‐level energy density of 310.2 Wh kg–1. This study provides a promising strategy to simultaneously tackle the challenges facing the Li anode and the sulfur cathode in LSBs.

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High-resolution synchrotron X-ray diffraction was used to study the phase transformations in titanium alloys. Three titanium alloys were investigated: Ti -6Al -4V, Ti -6Al -2Sn -4Zr -2Mo -0.08Si and b21s. Both room and high temperature measurements were performed. The room temperature experiments were performed to study the structure of the alloys after different heat treatments, namely as received (AR), furnace cooling (FC), water quenching (WQ) and water quenching followed by ageing. The a, a 0 , a 00 and b phases were observed in different combinations depending on the heat treatment conditions and the alloy studied. A multicomponent hexagonal close packed (hcp) a phase, with different c and the same a lattice parameters, was detected in Ti -6Al -4Vafter FC. High temperature synchrotron X-ray diffraction was used for 'in situ' study of the transformations on the sample surface at elevated temperatures. The results were used to trace the kinetics of surface oxidation and the concurrent phase transformations taking place under different conditions. The influence of the temperature and oxygen content on the lattice parameters of the a phase was derived and new data obtained on the coefficients of thermal expansion in the different directions of the hcp a phase, for Ti -6Al -4V and Ti -6Al -2Sn -4Zr -2Mo -0.08Si. D

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been reported. And for tandem solar cells, the PCE has reached 17%. [22] However, the vast majority of those device performances were obtained with layer-thicknesses at around 100 nm [23][24][25][26][27][28][29] and decreased drastically with the increase of the active layer thickness, which limits their application in the roll to roll large-scale solution printing technology. [30,31] Furthermore, 20%-40% of the incident photon flux were wasted in such a active layer thickness, [32] which directly limits the short circuit current density (J sc ) of the corresponding OSCs. Thus, it is necessary to develop high efficiency OSCs with tolerance of the active layer thickness. However, a lot of research work have proved that the charge collection efficiency of a device is inversely proportional to the square of the film thickness of the active layer. [33,34] It was reflected in the decline of fill factor (FF) with the increase of film thickness. Also, the J sc will decrease due to the severe bimolecular recombination. [35,36] Thus, it is still a challenge to obtain high efficiency devices with active layer thickness tolerance. To date, in the reported cases with active layer thickness tolerance, most are based on fullerene derivative acceptors and it has been found that the donor materials with high crystallinity and balanced mobility with fullerene derivative acceptors manifested better performance with high film thickness. [35][36][37][38] Compared with fullerene derivatives based OSCs, it is much more challenging to realize thick-film NFAs OSCs with high performance since the electron mobilities of NFAs are usually lower than that of fullerene derivative acceptors. [39,40] Thus, the charge transport and collection process in those NFA based thick films are not efficient. So far, great attentions have been drawn on the NFA based thick film OSCs and much progress have been made. For examples, Yip and co-workers reported devices based on PffBT4T-2OD:EH-IDTBR and realized a PCE of 9.1% with an active layer thickness of 300 nm by optimizing device architectures to overcome the space-charge effects. [41] Zhang and co-workers reported devices based on PM6:IDIC with PCEs of 11.9% under the film thickness of 150 nm and 11.3% under the condition of 255 nm condition. Although the device performance is good enough, the cases with thicker active layers Developing efficient organic solar cells (OSCs) with relatively thick active layer compatible with the roll to roll large area printing process is an inevitable requirement for the commercialization of this field. However, typical laboratory OSCs generally exhibit active layers with optimized thickness around 100 nm and very low thickness tolerance, which cannot be suitable for roll to roll process. In this work, high performance of thick-film organic solar cells employing a nonfullerene acceptor F-2Cl and a polymer donor PM6 is demonstrated. High power conversion efficiencies (PCEs) of 13.80% in the inverted structure device and 12.83% in the conventional structure device are achi...