Understanding the deformation mechanism of individual phases of a ZrTi-based bulk metallic glass matrix composite using in situ diffraction and imaging methods

The plasticity of a ZrTi-based bulk metallic glass composite consisting of glassy matrix and crystalline dendritic phase was studied in-situ under identical tensile loading conditions using scanning electron microscopy and synchrotron X-ray diffraction. A generic procedure was developed to separate the diffraction information of the crystalline phases away from that of the matrix and to precisely calculate the microscopic strains of the two phases at different macroscopic load steps. In this way, the time-evolved quantitative links between shear bands nucleation/propagation and the corresponding microscopic stress fields around them are established, providing more quantitative understanding on (1) how the shear bands are driven by the local stress field, and (2) the critical stresses required for the shear bands to nucleate in the crystalline phase, propagate through the crystalline/matrix interface, and finally into the matrix

The onset of plasticity of a Zr-based bulk metallic glass

The deformation behaviors of a Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glassy alloy under step-controlled tensile loads have been studied in situ and systematically using scanning electron microscopy and synchrotron X-ray diffraction. A circular hole, as a stress concentrator, was introduced in the middle of the gauge length of the sample to facilitate the creation of shear bands in a controllable way at the edge of the hole in situ imaging and diffraction studies could be carried out at the identical loads in a quasi-steady state manner. Pair distribution function was used to calculate the strains of different atomic coordination shells and the relative change of the bond lengths of different atomic pairs. The combined imaging and diffraction studies revealed that (1) the extension of solvent–solvent (Zr–Zr) atomic pairs under tension causes the nucleation of shear bands, and (2) the compressive stress field around the shear band tip effectively slows down the fast propagation of shear bands

FROM ACADEMY TO MARKET

In today’s world, research institutes are playing an increasingly important role in bringing new technology to market. Researchers and scientists are becoming more entrepreneurial in trying to commercialize their findings as new technologies and products. However, academic research focuses very little on the whole commercialization process and the management tools needed by entrepreneurial scientists. This paper looks at commercialization from the viewpoint of a group of scientists seeking to develop a new product from successful research. It takes a business eco-system perspective and presents a theoretical framework developed by mapping a wide range of literature. This framework is then compared to data collected during a longitudinal case study on the development of a fibre optic sensor analyser with application in the construction industry. A key finding is that relationships with partners and other supporting organizations need to be formed earlier than the literature currently suggests, and that an awareness of the business ecosystem within which the technology fits is as important to scientists as knowledge of available innovation and technology management tools. Hence an early focus on communication and partnership is highlighted as an important factor for commercialization success

Giant magnetocaloric effect and hysteresis loss in Mnx_xFe2−x_{2-x}P0.5_{0.5}Si0.5_{0.5} (xx = 0.7-1.2) microwires at ambient temperatures

Magnetocaloric microwires are very promising for energy-efficient magnetic refrigeration in micro electromechanical systems (MEMS) and nano electromechanical systems (NEMS). Creating microwires that exhibit large magnetocaloric effects around room temperature represents an important but challenging task. Here, we report a tunable giant magnetocaloric effect around room temperature in Mn$_x$Fe$_{2-x}$P$_{0.5}$Si$_{0.5}$ ($x$ = 0.7-1.2) microwires by utilizing a melt-extraction technique paired with thermal treatment and chemical engineering. The isothermal magnetic entropy change DeltaSiso and Curie temperature (TC) can be tuned by adjusting the Mn/Fe ratio. The TC varies from 351 to 190 K as x increases from 0.8 to 1.2. Among the compositions investigated, the x = 0.9 sample shows the largest value of DeltaSiso = 18.3 J kg$^{-1}$ K$^{-1}$ for a field change of 5 T around 300 K. After subtracting magnetic hysteresis loss, a large refrigerant capacity of ~284.6 J kg$^{-1}$ is achieved. Our study paves a new pathway for the design of novel magnetocaloric microwires for active magnetic refrigeration at ambient temperatures

The effect of cooling rate on the wear performance of a ZrCuAlAg bulk metallic glass

In the present work, the local atomic ordering and the wear performance of ZrCuAlAg bulk metallic glass (BMG) samples with different diameters have been studied using transmission electron microscopy (TEM) plus autocorrelation function analysis, and pin-on-disc dry sliding wear experiments. Differential scanning calorimetry and TEM studies show that smaller diameter BMG sample has higher free volume and less local atomic ordering. The wear experiments demonstrate that with the same chemical composition, the smaller BMG sample exhibits higher coefficient of friction, higher wear rate, and rougher worn surface than those of the larger ones. Compared with larger BMG sample, the faster cooling rate of the smaller sample results in looser atomic configuration with more free volume, which facilitates the formation of the shear bands, and thus leads to larger plasticity and lower wear resistance. The results provide more quantitative understanding on the relationship among the cooling rate, the local atomic ordering, and the wear performance of BMGs

Wear Behaviors of a Ti-Based Bulk Metallic Glass at Elevated Temperatures

Bulk metallic glasses (BMGs) often offer excellent physical, chemical, and mechanical properties such as high strength, high hardness, and good wear/corrosion resistance, stemming from their unique atomic configuration. These properties enable them to be a potential engineering material in a range of industrial applications. However, the wear behaviors must be considered in structural applications. Here, the wear tests of a TiZrNiCuBe bulk metallic glass at high temperatures were carried out. As the testing temperature increases, the wear rate of the studied BMG sample gradually decreases and the sample surface becomes smoother. Meanwhile, a higher applied normal load causes a higher wear rate. The wear mechanism evolves from the abrasive to adhesive mode with increase in the testing temperature. The results obtained here could shed more insights into the deformation mechanism of BMGs and thus extend their industrial uses in high-temperature environments

Effect of Pu-erh tea pomace on the composition and diversity of cecum microflora in Chahua chicken No. 2

Pu-erh tea pomace (PTP), a solid substance after extracting functional substances or steeping tea, is rich in crude protein, and crude fiber, and could be used as considerable bioactive substances in animal production. However, its application as poultry feed and its role in regulating the characteristics of gut microorganisms is unclear. The present study investigated the effects of PTP on growth performance and gut microbes of chicken. A total of 144 Chahua chickens No. 2 were individually housed and divided into three groups which were fed diets containing 0% (CK), 1% PTP (T1), and 2% PTP (T2), respectively. The serum and cecum contents were collected after slaughter for analysis. The results indicated that growth performance and carcass traits were not affected by the PTP content. Serum total triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels in the T1 and T2 groups were significantly lower than in the CK group (p < 0.05). The gut microbiota α-diversity in the T2 group was significantly lower than in the CK group (p < 0.05). Based on partial least squares-discriminant analysis (PLS-DA), we observed significant segregation in gut bacterial communities among the groups. At the phylum level, Bacteroidetes and Firmicutes were dominant in the cecum, occupying about 85% of the cecum flora. The relative abundance of Bacteroidetes tended to increase. At the genus level, the relative abundance of Bacteroides is the highest in the CK、T1 and T2 groups. The relative abundances of Bacteroides and Prevotellaceae_UCG-001 microorganisms in the T2 group were significantly higher than in the CK group (p < 0.05). However, the relative abundance of CHKCI001 microorganisms in the T2 group was significantly lower compared to the CK group (p < 0.05). TG content was significantly positively correlated with CHKCI001 relative abundance, and significantly negatively correlated with Prevotellaceae_UCG-001 relative abundance (p < 0.05). Moreover, the LDL-C content was significantly positively correlated with CHKCI001 relative abundance (p < 0.05). In conclusion, PTP could decrease the cholesterol levels in the blood by improving the composition of gut microbiota, which provides a reference for the application of PTP in the poultry industry