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The Cu-12Al-4Ni-1Mn-xB（x=0%，0.1%，0.2%，0.3%，mass fraction，the same below） shape memory alloys were prepared by vacuum arc melting furnace after introducing trace boron element into the alloy. The influence of boron addition on the microstructure， phase transformation， and mechanical properties of the alloy was investigated. The results show that the addition of boron significantly refines the grain size， with the grain size decreasing from hundreds of microns to （11±3.45） μm. The phase transformation temperature shifts to the high-temperature side after boron is added， indicating that the phase transformation process requires higher thermal activation energy. When the boron content is 0.2%， the microhardness of the alloy is enhanced， from （301.7±2.6）HV without adding boron element to （334.3±3.4）HV， which is attributed to grain refinement and the precipitation of hard and brittle borides. The tensile fracture strength and elongation are greatly improved， with the fracture strength increasing from （320±2.6） MPa to （788±17） MPa， and the elongation increasing from （1.44±0.05）% to （3.74±0.12）%. After solid solution annealing， the fracture strength and the elongation are both further increased to （856±10.7）MPa and （5.78±0.16）%， respectively. Analysis indicates that grain refinement strengthening， precipitation strengthening of borides， and solid solution strengthening are the main mechanisms for the improvement of mechanical properties. The fracture mode of the alloy shifts from brittle fracture to ductile fracture.

CuAlMn shape memory alloys have specific target demands in various fields due to excellent thermal stability and high damping properties.However， the mechanical property of the alloy is severely weakened due to the intergranular fracture arising from the coarse grain size. To improve the mechanical properties， the Cu-11.36Al-5Mn-xY （x=0-3， mass fraction/%，the same below） alloys were prepared by using a vacuum arc melting furnace by introducing rare earth Y element. The microstructure of the as-cast CuAlMn alloy was subsequently tailored and homogenized through solid solution and aging treatment. The phase transformation， phase composition， and microstructure of the alloy were respectively characterized by DSC， XRD， metallography and SEM observations. The hardness and mechanical properties of the alloy were tested by using a microhardness tester and a universal materials testing machine. Results show that the addition of Y element effectively refines the CuAlMn alloy grain， and the grain size even reduces from several hundred μm to around 10 μm. The grain refinement is mainly associated with the increased grain nucleation areas and the inhibition of grain growth during the cooling process. Moreover， quite numbers of Y-containing precipitates with the network structure are formed and distributed along the grain boundaries. The hardness of the alloy increases with the enhancement of Y element addition， which is associated with the precipitation of a large amount of hard and brittle containing Y phases.The hardness of the solution-aged sample is higher than that of the cast sample， due to the precipitate distribution throughout the entire matrix and higher volume fraction of precipitates for the former sample.In addition， the compressive and tensile fracture strength of the alloy are significantly improved when the Y content is in the range of 0.1%-0.4%. The strengthening mechanism can be understood by grain refinement strengthening， precipitation strengthening and solution strengthening. The compressive fracture strain of the alloy reaches its maximum when the Y content is 0.4%， while the elongation after fracture exhibits the maximum value with Y content of 0.1%. The changing trend is closely related to the coupling effect between grain refinement and precipitation phases.

The Ti50-0.5xNi50-0.5xZrx series alloys were prepared by vacuum arc melting and subsequent suction casting. Metallographic observation and tensile mechanical tests show that adding trace amount of Zr can reduce grain size and increase higher tensile strength and elongation， however， excessive Zr content can easily lead to the formation of brittle intermetallic compound Zr2Ni and reduce its mechanical properties. The multi-pass cold-rolling deformation and annealing treatment on Ti49.9Ni49.9Zr0.2 alloy were carried out. The results show that the tensile strength σb and the elongation δ of the Ti50－0.5xNi50－0.5xZrx alloys increase with the increase of cold-rolling deformation. Compared with the unrolled alloys， after four-passes cold-rolling deformation， the tensile strength and the elongation after fracture of the alloys increase from 561 MPa，1.14% to 768 MPa ，35.1%，respectively.Microscopic observation of SEM and TEM show that the hard Ti2Ni particles distributed along the grain boundaries during the cold rolling process are sheared and broken， resulting in a discontinuous distribution of refinement. After 700 ℃ annealing process， the deformed microstructure has recovery recrystallization， resulting in the appearance of nanocrystalline and amorphous regions. Moreover， a large number of plate-like nano-twin structures and high-density dislocations appear in the TiNi matrix with the increase of cold-rolling deformation.

Metal-matrix composites with high damping capacity and excellent energy absorption properties have extensive application requirements. Porous TiNi shape memory alloys with a three-dimensional connected structure were firstly prepared by powder metallurgy technology consisting of "uniform-mixing, compaction, dissolution and sintering" four stages. Then, the novel Acrylic/TiNi composites were manufactured in light of vacuum negative pressure infiltration technology. The damping properties were characterized by internal friction. It was found that Acrylic/TiNi composites exhibit a much higher damping capacity than that of corresponding TiNi porous materials, especially in around room temperature zone. It was rationalized that the great improvement of the damping capacity is originated from the intrinsic high-damping of Acrylic phase as well as induced massive interface damping between TiNi porous matrix and Acrylic phases. The quasi-static compressive mechanical measurement shows that Acrylic/TiNi composites can achieve energy absorption efficiency similar to that of TiNi porous alloy, the reason of which is confirmed to be associated with the longer and smoother compression plateau area of TiNi composites. In addition, the full penetration of the Acrylic reinforced phase greatly enhances the energy absorption capacity and yield strength of the composites. Deformation mechanism analysis of the TiNi composites indicates that the mutual compensation and coupling between porous matrix and Acrylic fillings during the compressive process can be considered to account for the improved energy absorption characteristics.

BaBiNb5O15- based oxide ion conductors have shown promise for solid fuel cell applications at medium temperatures. In this study, BaBi0.98Sr0.02Nb5-xTixO15-δ (x = 0.02, 0.04, 0.05, 0.06, 0.08) samples were prepared by the conventional solid-state synthesis with two-step sintering method. The electrical properties and oxygen relaxation behaviors of the BaBi0.98Sr0.02Nb5-xTixO15-δ samples were investigated. With increasing the Ti content, the bulk conductivity of the BaBi0.98Sr0.02Nb5-xTixO15-δ samples showed a trend of increasing first and then decreasing. When the doped Ti content reached 5 mol%, the highest bulk conductivity of BaBi0.98Sr0.02Nb5-xTixO15-δ samples can be got, 5.27 × 10−5 S/cm at 773 K. According to the dielectric relaxation spectroscopy measurement, the BaBi0.98Sr0.02Nb4.95Ti0.05O15-δ sample exhibits the higher moveable oxygen vacancy concentration and mobility of oxygen vacancies. This could be the possible reason that there is the highest bulk conductivity in the BaBi0.98Sr0.02Nb4.95Ti0.05O15-δ sample. Additionally, the influence of sintering temperature on the electrical properties of the BaBi0.98Sr0.02Nb4.95Ti0.05O15-δ compound was investigated. When the BaBi0.98Sr0.02Nb4.95Ti0.05O15-δ sample is sintered at a temperature of 1423 K, it exhibits the best bulk conductivity and total conductivity. [ABSTRACT FROM AUTHOR]

Ti-modified BaBiNb0.95Ti0.05O15-δ (BBN-Ti5-TS) oxygen ion conductors with tungsten bronze structure were prepared by solid-phase reaction and two-step sintering-assisted sintering method. The electrical conductivity and oxygen ion diffusion of the Ti-modified BaBiNb5O15 (BBN) specimen were investigated. Both the grain conductivity and total conductivity of the BBN-Ti5-TS specimen are enhanced relative to the BBN compound. At 623 K, the BBN-Ti5-TS specimen grain conductivity can get up to 1.28 × 10–4 S/cm, half an order of magnitude higher of the pristine BBN specimen. A relaxation peak associated with thermal activation was observed in the BBN-Ti5-TS specimen with a relaxation activation energy parameter of E = 0.44 eV. The value is slightly lower than the activation energy of oxygen ion migration in the parent compound. Combining the relaxation parameter and structural analysis, the titanium doping and two-step sintering-assisted sintering can reduce the energy barrier for oxygen ion diffusion to a certain extent. Compared with the BBN specimen, the lower oxygen diffusion activation energy and smaller grain size are the main reasons for the significant increase in the conductivity of the BBN-Ti5-TS compound. [ABSTRACT FROM AUTHOR]