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Selective laser melting(SLM) is a powerful additive manufacturing(AM) technology, of which the most prominent advantage is the ability to produce components with a complex geometry. The service performances of the SLM-processed components depend on the microstructure and surface quality. In this work, the microstructures, mechanical properties, and fracture behaviors of SLM-processed Ti-6 Al-4 V alloy under machined and as-built surfaces after annealing treatments and hot isostatic pressing(HIP) were investigated. The microstructures were analyzed by optical microscope(OM), scanning electron microscope(SEM) and transmission electron microscopy(TEM). The mechanical properties were measured by tensile testing at room temperature. The results indicate that the as-deposited microstructures are characterized by columnar grains and fine brittle martensite and the asdeposited properties present high strength, low ductility and obvious anisotropy. After annealing at 800-900°C for 2-4 h and HIP at 920°C/100 MPa for 2 h, the brittle martensite could be transformed into ductile lamellar(α+β) microstructure and the static tensile properties of SLM-processed Ti-6 Al-4 V alloys in the machined condition could be comparable to that of wrought materials. Even after HIP treatment, the as-built surfaces could decrease the ductility and reduction of area of SLM-processed Ti-6 Al-4 V alloys to 9.2% and 20%, respectively. The crack initiation could occur at the columnar grain boundaries or at the as-built surfaces. The lamellar(α+β) microstructures and columnar grains could hinder or distort the crack propagation path during tensile tests. 相似文献
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目的:探讨大枣多肽裂解液抗肿瘤作用并初步探讨其抗肿瘤机制,为其临床应用提供实验室依据。方法:将接种肿瘤后的小鼠随机分为5组,每组10只小鼠,雌雄各半,给药10d,停药后24h处死动物,称小鼠体重,剥离小鼠右腋下皮下组织,摘出肿瘤,称瘤重,测定生化指标。结果:对肉瘤(S180)、肝癌(Hep)、胃癌(MFC)细胞荷瘤小鼠肿瘤生长具有明显的抑制作用,其中对S180作用显著,较低剂量即可显示明显作用,延长S180荷瘤鼠生存时间;同时可增加吞噬指数α、廓清指数K、及胸腺系数;对体外淋巴细胞转化功能亦有增强作用。结论:大枣多肽裂解液具有明显抗肿瘤活性。 相似文献
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利用XR6702型大孔吸附树脂精制黑豆花青素,并研究其降血糖活性。黑豆花青素精制工艺参数为,吸附条件:最佳吸附树脂为XR6702型大孔吸附树脂,吸附浓度2 mg/mL,吸附pH 3.0,上柱体积15 mL;解吸条件:60%乙醇水溶液(pH 4.0),洗脱流速1.5 mL/min,精制后黑豆花青素纯度为84.92%,精制黑豆花青素对α-葡萄糖苷酶和α-胰淀粉酶的抑制率分别为91.36%和89.17%,并表现出良好的剂量效应关系,抑制作用强于阿卡波糖,黑豆花青素在体外表现出较好的降血糖活性。 相似文献
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文章简要介绍了利用ATUOCAD求梁截面惯性矩I和抗弯截面模量W的方法,并通过实例计算证明了此方法的可行性和准确性,可供有关煤矿机械设计人员在求梁的最大应力时使用。 相似文献
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谭白英 《武汉冶金管理干部学院学报》2005,15(4):17-19
楚皇城遗址旅游开发有着坚实的主体文化--楚文化的根基,具备文物保护规划可靠可行的方案依据,其旅游开发有着良好的技术条件和发展前景,采用遗址公园形式、紧密结合文化内涵的开发手段,在选址和环境保护方面具有科学性和可行性. 相似文献
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文中研究了重力垂直熔融拉锥法中不同温度、不同拉伸力工艺条件对聚合物光纤热预
拉锥特性的影响。实验表明:加热区中心温度为214℃附近和拉伸力为1. 40g左右时, PMMA聚合物光纤拉伸过程容易控制,并且具有良好的光学质量。 相似文献