放电等离子烧结Ti-35Nb-7Zr-xHA复合材料的力学性能与腐蚀性能（英文）

为了改善Ti-Nb-Zr合金的生物活性,采用放电等离子烧结(SPS)制备了Ti-35Nb-7Zr-xHA(羟基磷灰石,x=5,10,15,20,质量分数,%)复合材料。借助XRD、SEM、力学测试以及电化学测试手段研究了HA含量对复合材料显微组织、力学性能和腐蚀性能。结果表明,所有复合材料的物相主要由β-Ti基体、α-Ti和金属-陶瓷相(CaO,CaTiO_3,CaZrO_3,TixPy等)组成,此外,含15%HA和20%HA的复合材料中出现了少量残余的HA;随着HA含量的增加,复合材料的抗压强度均高于1400MPa,复合材料(5%-15%HA)的弹性模量呈较小变化趋势(46-52GPa),更加接近人骨的弹性模量。在Hank’s溶液中的电化学试验表明,HA含量为15%时,复合材料的钝化电流密度和腐蚀电流密度较低,显示了较好的腐蚀性能。因此,Ti-35Nb-7Zr-15HA复合材料可作为一种骨科植入手术中较好的替代材料。

Effect of solution treatment on microstructure and mechanical properties of as-cast Al-12Si-4Cu-2Ni-0.8Mg-0.2Gd alloy

Effect of solution treatment on microstructure and mechanical properties of Al-12Si-4Cu-2Ni-0.8Mg-0.2Gd alloy was investigated.Results show the Si particles become stable and more intermetallic compounds dissolve in the matrix after solution treatment at 500℃for 2 h followed by 540℃for 3 h(T4).The skeleton-like Al_(3)CuNi develops into two parts in the T4 alloy:one is Al_(3)CuNi which has the framework shape;the other is intermetallics including the Al_(3)CuNi(size:5-10μm)and AlSiCuNiGd phases(size:≤5μm)with complex structure.Adding 0.2%Gd can improve the mechanical properties of the alloys after two-step solution treatment(500℃/2 h followed by 540℃/3 h),the hardness of the alloy increases from 130.9 HV to 135.8 HV compared with the alloy with one-step solution treatment(500℃/2 h),the engineering strength increases from 335.45 MPa to 352.03 MPa and the fracture engineering strain increases from 1.44%to 1.67%.

Properties of Fe-Mn-Al alloys with different Mn contents using density functional theory

The chemical stability,electronic structures,mechanical properties and Debye temperature of Fe-MnAl alloys were investigated using first-principles calculations.The formation enthalpy and cohesive energy are negative for Fe-Mn-Al alloys,showing that they are thermodynamically stable.FeAl has the lowest formation enthalpy,indicating that FeAl is the most stable alloy in the Fe-Mn-Al system.The partial density of states,total density of states and electron density distribution maps were used to analyze the physical properties of the Fe-MnAl alloys.A combination of mainly covalent and metallic bonds exists in these Fe-Mn-Al alloys,resulting in good electronic conductivity,high melting points,and high hardness.These alloys display disparate anisotropy due to the calculated different shapes of the 3D curved surface of the Young's modulus and anisotropic index.FeAl has the highest bulk modulus,shear modulus and Yong's modulus of 187.1,119.8 and 296.2 GPa,respectively.Further,the Debye temperatures and sound velocity of these Fe-Mn-Al compounds were explored.

Effects of Rare Earth,Titanium,and Magnesium Additions on Microstructures and Properties of High-boron Medium-carbon Alloy

In order to improve the toughness and wear resistance of high-boron medium-carbon alloy （HBMCA）, a novel wear-resistant HBMCA comprising granular borocarbide was obtained by titanium, magnesium, and rare earth modifications. These modifications gave rise to greatly refined as-cast eutectic borocarbide structures and a less interconnected continuous borocarbide network. Heat treatment mostly produced broken and spheriodized borocarbides that tended to exist as isolated particles in modified HBMCA. The heat treated modified HBMCA exhibited enhanced hardness than pristine and impact toughness was improved significantly to 12.5 J/cm^2. In addition, it displayed 2.39 and 1.7 times greater wear resistance than high-speed steel （HSS） and high nickel-chromium alloy steel （Cr25） at high temperature （500℃）, respectively. Here, the modification mechanisms involving Re2O3, TiN, and MgO/ MgS heterogeneous nuclei were discussed.

Characterizations on Mechanical Properties and In Vitro Bioactivity of Biomedical Ti–Nb–Zr–CPP Composites Fabricated by Spark Plasma Sintering

To alleviate the bio-inert of Ti alloys as hard tissue implants, Ti–35Nb–7Zr–xCPP（calcium pyrophosphate,x = 5, 10, 15, 20 wt%） composites were prepared by mechanical alloying（MA） and following spark plasma sintering（SPS）. Mechanical behaviours and in vitro bioactivity of these composites were investigated systematically. Results showed that the composites consisted of β-Ti matrix, α-Ti, and metal–ceramic phases such as CaO, CaTiO3, CaZrO3, and TixPy. With increasing CPP content, the composites had higher strength（over 1500 MPa） and higher elastic modulus, but suffered almost zero plastic deformation together with lower relative density. When the CPP contents were 5 and 10 wt%,the compressive elastic moduli were 44 and 48 GPa, respectively, which were close to those of natural bones. However, the compressive elastic modulus of the composites increased significantly when CPP contents exceed 10 wt%, thus deteriorating the mechanical compatibility of the composites owing to more α-Ti and metal–ceramic phases. Besides, the surface of Ti–35Nb–7Zr–10CPP composite was deposited as a homogeneous apatite layer during soaking in simulated body fluid（SBF）. It indicates a good bioactivity between the implant materials and living bones.