铝硅合金流变模型及应力－应变本构关系的研究

通过Ａｌ－Ｓｉ合金准固态流变性能的测试，建立了该合金准固态流变模型，并推导了轴对称铝硅合金铸件凝固过程应力－应变本构方程，为开展铸件凝固过程热应力数值模拟和热裂预测提供了可靠的理论依据。     

电磁搅拌与浇注温度对半固态A356铝合金中微量稀土细化初生相的影响

在不同浇注温度和电磁搅拌制度下制备了A356铝合金半固态浆料,研究了微量稀土下浇注温度、电磁搅拌频率和时间对半固态A356铝合金初生相形貌及力学性能的影响。结果表明,通过优化半固态制浆工艺条件减少稀土的加入量是可行的,实验表明稀土微量化的合适工艺方案是:浇注温度为630℃,电磁搅拌频率为30Hz,搅拌时间为8s。此时,加入量为0.3%的稀土La细化效果和常规加入量为0.4%La的低过热度浇注的相当,其力学性能也基本相同。     

半固态成形工艺特点及发展现状

半固态成形技术充分利用金属材料在半固态温度区间特殊的微观组织和成形性能,能够在较低的成形载荷下实现复杂构件的高效近净成形,该技术的应用对于提高金属材料的质量利用率和性能利用率、延长模具寿命、节能减排等方面具有重要的作用。主要介绍了半固态成形技术的历史沿革、半固态成形技术的分类、半固态金属坯料浆料的制备工艺、有色金属材料和钢铁材料的半固态成形技术开发以及应用情况,最后提出了半固态成形技术所面临的挑战和机遇。     

3D Printing and Nanotechnology: A Multiscale Alliance in Personalized Medicine

3D printing and nanotechnology have been two important tools in the development of therapeutic approaches for personalized medicine. More recently, their alliance has been improved in an effort to build innovative, versatile, multifunctional, and/or smart medical and pharmaceutical products. Therefore, an extensive review about scientific studies that ally 3D printing and nanomaterials in the development of new approaches for pharmaceutical and medical applications for the treatment and prevention of diseases is presented here. The articles are classified into five categories according to their main application: Cell growth and tissue engineering, antimicrobial, drug delivery, stimulus-response, and theranostics. Semisolid extrusion, inorganic nanoparticles, and cell growth and tissue engineering are the most reported 3D printing technique, type of nanomaterial, and application, respectively. The increase in papers dedicated to these areas is also notable, especially in the 2019 and 2020, when semisolid extrusion became the most used technique, overcoming fused deposition modelling. In fact, this review highlights that the possibility of an alliance between 3D printing and nanotechnology for the production of multiscale materials is undoubtedly a great opportunity for knowledge and innovation in the pharmaceutical and medical area.     

Basic rules for rheologic forging process of semisolid alloy

Semisolid mold forging is a major type of semisolid processing, which is different from neither traditional mold forging nor traditional permanent casting. However, processing defects are often seen in work pieces because of lacking available rules for the process design and control. Some basic rules for the process design and control, simply named the shortest flowing length, pressure filling and the minimum uplifting mold pressure, are advanced in the paper based on amount of researches and experiments. The equations to determine the major process parameters are given out such as the filling pressure, forming pressure and locking mold pressure for the process design and control. The rules and equations are experimentally proved available and applicable by several actual work pieces produced by the semisolid forging process.     

钢的半固态单轴压缩变形规律

用Gleeble-1500热模拟实验机研究了不同变形速率、不同变形温度以及不同变形量下60Si2Mn钢的半固态应力与应变的变化规律，并通过金相观察分析了压缩变形后钢的半固态显微组织。结果发现钢的半固态压缩变形特征为：随着变形温度的不同呈粘塑性流动；在不同的变形速率下，初始变形阶段的应力变化是基本一致的，即半固态的钢先呈现出线弹性的变形响应，随后呈现出不同软化程度的粘性流动变形响应；变形量对钢的半固态变形特征影响显著。在适宜的温度及变形量范围内，半固态的钢呈粘性流动。笔者认为：半固态的钢因其特殊的组织特点，会形成疏松且不稳定的晶粒聚集结构。在外界作用下，该聚集结构将被破坏，从而导致钢的半固态浆料的表观粘度下降，即呈现出“剪切变稀”的触变特性。     

自孕育法制备AZ31镁合金半固态流变成形组织(英文)

采用新型自孕育流变铸造技术对变形镁合金半固态组织进行控制。该工艺过程为将合金熔体与一定量的合金固体颗粒(自孕育剂)混合,然后将混合金属通过一个多流股导流器浇入铸型或收集器。结果表明:采用自孕育工艺,合金熔体处理温度690~710℃,孕育剂的加入量为3%~7%时能有效将AZ31镁合金传统铸造中的粗大枝晶组织转变为细小、近球状的非枝晶组织;当合金熔体处理温度较高时,增加孕育剂的加入量或减小导流器的倾斜角度有利于获得非枝晶组织。自孕育工艺制备的AZ31镁合金半固态浆料在620℃等温保温30s后能有效改善初生α-Mg颗粒的圆整度;延长保温时间有助于减小颗粒的圆整度,但同时颗粒发生粗化。利用Lifshitz-Slyozov-Wagner(LSW)理论对初生相颗粒在等温保温过程中的组织圆整、粗化过程进行了分析。     

轿车用金属材料重点解析

叙述了近年来汽车结构件用金属材料的研究现状。简介了国内外在研制双相钢,相变诱发塑性钢,烘烤硬化钢和IF钢的进展。介绍了半固态成形技术（SSF）以及采用该技术制造铝合金部件时的工艺关键。阐述了国外将半固态技术成功地应用于汽车工业上的实例。为便于交流、文中也简介了上海大学材料学院在研究汽车用金属材料方面的工作。     

Preparation of Semisolid Slurry for Stainless Steel 1Cr18Ni9Ti

The preparation of nondendritic semisolid slurry for stainless steel 1Crl8Ni9Ti was studied. The experiments show that when stirred for 2--3 min under the test condition, the semisolid slurry with solid of about 50% and spherical primary austenite in size of 100--200μm can be obtained, and besides the slurry is easy to flow out through the bottom hole of thestirring chamber. More homogeneous temperature fields and solute fields of stainless steel 1Crl8Ni9Ti melt appear because of the electromagnetic stirring, which restrains the formation of large primary austenitic dendrites and creates a base to form spherical crystals of primary austenite. The stronger temperature fluctuation in the melt containing many stirring-initiated rosette primary austenitic grains, together with the simultaneous remelting of the secondary arm roots primarily account for the deposition of the spherical primary austenitic grains.     

剪切速率增稠半固态合金浆料的流变力学模型

半固态合金浆料的本质特性依靠宏观因素。这些因素控制着材料的流变行为。它们又可转化为内变量和外变量,内变量包括固相颗粒的团块化程度、流体粘度、颗粒尺寸、颗粒形貌和颗粒尺寸的分析,外变量包括和剪切速度。在原来的简单模型上,根据半固态合金浆料的不同特性,得出不同条件下的新模型。