In this paper, the effect of Ni (0, 0.5 and 1.0 wt%) additions on the microstructure, mechanical properties and electrical conductivity of cast and extruded Al-MM-Sb alloy is studied using field emission scanning electron microscopy, and a universal tensile testing machine. Molten aluminum alloy is maintained at 750 oC and then poured into a mold at 200 oC. Aluminum alloys are hot-extruded into a rod that is 12 mm in diameter with a reduction ratio of 39:1 at 550 oC. The addition of Ni results in the formation of Al11RE3, AlSb and Al3Ni intermetallic compounds; the area fraction of these intermetallic compounds increases with increasing Ni contents. As the amount of Ni increases, the average grain sizes of the extruded Al alloy decrease to 1359, 536, and 153 μm, and the high-angle grain boundary fractions increase to 8, 20, and 34 %. As the Ni content increases from 0 to 1.0 wt%, the electrical conductivity is not significantly different, with values from 57.4 to 57.1 % IACS.

The mechanical behavior and microstructural evolution during high temperature tensile deformation of recrystallizedNi3Al polycrystals doped with boron were investigated as functions of initial grain size, tensile strain rate and temperature. Inorder to obtain more precise information on the deformation mechanism, tensile specimens were rapidly quenched immediatelyafter deformation at a cooling rate of more than 2000Ks−1, and were then observed by transmission electron microscopy (TEM).Mechanical tests in the range of 923K to 1012K were carried out in a vacuum of less than 3×10−4 Pa using an Instron-typemachine with various but constant cross head speeds corresponding to the initial strain rates from 1.0×10−4 to 3.1×10−5s−1.After heating to deformation temperature, the specimen was kept for more than 1.8ks before testing. The following results wereobtained: (1) Flow behavior was affected by initial strain size; with decreasing initial grain size, the level of a stress peak inthe true stress-true strain curve decreased, the steady state region was enlarged and elongation increased. (2) On the basis ofTEM observation of rapidly quenched specimens, it was confirmed that dynamic recrystallization certainly occurred ondeformation of fine-grained (3.3µm) and intermediate-grained (5.0µm) specimens at an initial strain rate of 3.1×10−5s−1 andat 973K. (3) There were some dislocation-free grains among the new recrystallized grains. The obtained results suggest thatboth dynamic recrystallization and grain boundary sliding are operative during high temperature deformation.

In this work, effect of various process-control agents (PCAs) on the mechanical alloying of amorphous alloy of has been investigated. The dependence of the particle shape, size and crystallization behavior of the amorphous alloy powders on the type of PCAs and their concentrations was investigated by using X-ray diffraction, field-emission scanning electron microscopy and differential scanning calorimetry. It was found that the additive of toluene could affect positively the amorphization and thermally induced crystallization processes, as well as the size refinement, morphology and particle-size distribution of as-milled powders in comparison with alloy obtained without PCA.

The amorphization process and the thermal properties of amorphous TiCuNiAl powder during milling by mechanical alloying were examined by X-ray diffractometry (XRD), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). The chemical composition of the samples was examined by an energy dispersive X-ray spectrometry (EDX) facility attached to the scanning electron microscope (SEM). The as-milled powders showed a broad peak (2 = 42.4) with crystalline size of about 5.0 nm in the XRD patterns. The entire milling process could be divided into three different stages: agglomeration (0 < t 3 h), disintegration (3 h < t 20 h), and homogenization (20 h < t 40 h) (t: milling time). In the DSC experiment, the peak temperature T and crystallization temperature T were 466.9 and 444.3, respectively, and the values of T, and T increased with a heating rate (HR). The activation energies of crystallization for the as-milled powder was 291.5 kJ/mol for T.

Al-Ni alloy nano powders have been produced by the electrical explosion of Ni-plated Al wire. The porous nano particles were prepared by leaching for Al-Ni alloy nano powders in 20wt% NaOH aqueous solution. The structural properties of leached porous nano powder were investigated by nitrogen physisorption, X-ray diffraction (XRD) and transmission Microscope (TEM). The surface areas of the leached powders were increased with amounts of AI in alloys. The pore size distributions of these powders were exhibited maxima at range of pore diameters 3.0 to 3.5 nm from the desorption isotherm. The maximum values of those were decreased with amounts of Al in alloys.

The effect of extrusion temperature on the microstructure and mechanical properties were studied in He-gas atomized alloy powders and their extruded bars using SEM, tensile testing and thermal expansion testing. The extruded bar of alloy consists of a mixed structure in which fine Si particles with a particle size below 20∼500nm and very fine compounds with a particle size below 200nm are homogeneously dispersed in Al martix with a grain size below 500nm. With increasing extrusion temperature, the microstructural scale was decreased. The ultimate tensile strength of the alloy bars has incresed with decreasing extrusion temperature from 500 to 35 and alloy extreded at 35 shows a highest tensile strength of 810 MPa due to the fine namostructure. The addition of Ni and Ce decreased the coefficients of thermal expansion and the effects of extression temperature on the thermal expansion were not significant.

Al-l4wt.%Ni-l4wt.% Mm(Mm=misch metal) alloy powders rapidly solidified by the gas atomization method were subjected to mechanical milling(MM). The morphology, microstructure and hardness of the powders were investigated as a function of milling time using scanning electron microscopy(SEM), transmission electron microscopy(TEM) and Vickers microhardness tester. Microstructural evolution in gas-atomized Al-l4wt.%Ni-l4wt.% Mm(Mm=misch metal) alloy powders was studied during mechanical milling. It was noted that the as-solidified particle size of decreases during the first 48 hours and then increases up to 72 hours of milling due to cold bonding and subsequently there was continuous refinement to on milling to 200 hours. Two microstructurally different zones, Zone A, which is fine microstructure area and Zone B, which has the structure of the as-solidified powder, were observed. The average thickness of the Zone A layer increased from about 10 to in the powder milled for 24 hours. Increasing the milling time to 72 hours resulted in the formation of a thicker and more uniform Zone A layer, whose thickness increased to about . The TEM micrograph of ball milled powder for 200 hours shows formation of nano-particles, less than 20 nm in size, embedded in an Al matrix.

Processing and properties of composites with Ni-Fe content of 10 and 15 wt% were investigated. Homogeneous powder mixtures of /Ni-Fe alloy were prepared by the solution-chemistry route using , and powders. Microstructural observation of composite powder revealed that Ni-Fe alloy particles with a size of 20nm were homogeneously dispersed on powder surfaces. Hot-pressed composites showed enhanced fracture toughness and magnetic response. The properties are discussed based on the observed microstructural characteristics

급냉응고방식으로 제조한 비정질 Z r62-xN i10C u20A l8 Tix (x=3, 6, 9at%) 합금을 사용하여 열적, 기계적 성질을 조사하였다. 시효온도에 따른 결정화 거동은 Ti 3at%에서는 비정질→비정질+Z r2A l3+Zr+(Ni,Ti)→Z r2Cu+Al+(Ni,Ti)의 결정화 거동을 나타내었으며, Ti 6at%에서는 비정질→비정질+Al→A l2Ti+NiZr+CuTi, Ti 9at%에서는 비정질→비정질+Zr+Al→Zr+A l2Zr+Al Ti3+CuTi의 결정화 거동을 보였다. 시효온도가 증가할수록 비정질 모상에 석출상의 체적율( Vf )이 증가하고 그에 따라 비커스 경도 ( Hv )간이 증가하였다. 파괴인장강도(σf )는 Vf 의 증가에 따라 증가하다가 Z r59A l10N i20C u8 Ti3은 Vf =38%에서 1219MPa의 최대값을 보이고, Z r56A l10N i20C u8 Ti6은 Vf =2%에서 1203MPa의 최대값을 보이고, Z r53A l10N i20C u8 Ti9 Vf =5%에서 1350MPa의 최대값을 나타낸 후 그 이상의 Vf 에서는 급격히 감소하였다. σf 가 급격히 감소하는 Vf 와 연성 파면에서 취성파면으로 천이되는 Vf 가 일치하였다.f/가 일치하였다.

Ni-36at.%Al을 함유하는 나도 결정립의 NiAl 합금이 기계적 합금화법에 의해 제조되었다. 제조된 분말은 방전 플라즈마 소결법에 의해 만들어졌다. 상변테에 영향을 주는 인자는 냉각속도와 열처리 시간의 조건으로 논의되었다. 소결체의 상변태 거동은 시차 열분석(DSC)과 X-선 회절(XRD) 분석법에 의해 조사되었다. 미세구조는 주사전자현미경(SEM)으로 관찰되었다. 마르텐사이트 격사상수와 체적 분율은 X-선 회절분석법 중 직접비교법에 의해 계산되었다.