The martensitic phases and their structure of the heat treated U- 10%Zr alloy have been studied. The α′ martensite phase with orthorhombic structure and the high plastici-ty α″ martensite phase with monoclinic form can be obtained by water-quenching and an-nealing in γ single phase section or γl+γ2 miscibility gap and β+γ2 or α+γ2 phase section, respectively. Owing to forming martensite phase, both the hardness of the sample and the lat-tice parameters of α phase will be changed.

The electronic structures of cluster Fe8 with D6h symmetry and Fe15 with Oh symmetry have been studied by MS-Xα method. The results show that (1) The exchange splittings of the d-band and the magnetic moments of the Fe-atoms are different in the two clusters; (2) The charge distribution in both clusters is not uniform, showing that the electrons are transferred from peripheral atoms to inner atoms, and the spin-direction (up or down) of the electrons transferred is in accordance with the symmetric characteristics of the clusters.

Microstructure and texture changes during secondary recrystallization of MGH754 alloy were studied. The results show that the as-extruded alloy has a fine equiaxed grain structure and weak texture. After secondary recrystallization annealing, coarse elon-gated grain structure parallel to the extrution dircction and strong texture components existed. The content of { 110} <001 > and { 100} <001> texture components increased, while {110} <111>, {110} <112> and { 112} <111> texture components decreased with the in-creasing of annealing time. The longitudinal direction of MGH754 bar is mainly <001> orientation.

The variability of intrinsic and extrinsic toughening levels has been derived for 8090 Al-Li alloy. The tensile properties and plane stress fracture toughness have been deter-mined for alloy 8090 sheets with various contents of impurities and Ce addition. Impurities Fe, Si and Na, K show an evident behavior to decrease the intrinsic toughening level and the fracture toughness even though the impurities could produce the extrinsic toughening effi-ciency to a certain degree. The intrinsic toughening level could be enhanced but the extrinsic toughening level is reduced by adding minor Ce element into alloy 8090 containing higher concentration of impurities. The intrinsic and extrinsic toughening levels are increased and the fracture toughness improved when the alloy containing higher concentration of impurities is modified by a fixed Ce content.

The nanometre-sized Fe-Cu supersaturated solid solutions were prepared by chemical reduction. There is a small amount of boron dissolved in the alloys. The solid solu-bility of fcc-phase is largely extended to about an atomic ratio of 4: 1 for Fe and Cu. The range of fcc phase in the Fe-Cu alloy goes beyond the scope of that prepared by mechanical alloying. The fcc phase was found to be rather stable during heat treatment. The large solubil-ity extending and high stability of fcc phase are caused by the small amount of boron con-tained in the alloys.

The cyclic deformation behavior of four types of copper bicrystals was; investi-gated over a shear strain amplitude (γpl) range from about 1 .66 x 1O-4 to about 9.1 x '1O-3. Ex-perimental results show that the cyclic deformation behavior of three types of ' copper bicrystals with grain boundaries parallel to loading axis is similar to that of a copper single crystal oriented for single slip, and the cyclic stress-strain (CSS) curves all contain a plateau. But the platcau stresses of the bicrystals are higher than the typical value 28 MPa off a single slip copper single crystal and are different from each other. While, for a bicrystals containing a grain boundary perpendicular to loading axis and two component crystals one one which is oriented for single slip and another is oriented for double slip, there is no plateau in the CSS curve, and it was found that the CSS quite is quite similar to that of copper polycrystals. Ob-servation of surface morphology shows that the above cyclic deformation behavior of the four types of bicrystals is closely related to the occurrence of double slip or multiple slip due to the constraint of grain boundary and the different degrees of dislocation interaction between the operative slip systems.

Surface morphology of fatigued copper bicrystals was investigated by a scan-ning electron microscopy(SEM). It was found that the grain boundaries are the preferred sites for fatigue crack initiation in the fatigued bicrystals. A large number of fatigue microcracks was observed at the sites of grain boundaries where slip bands impinged, especially at the sites where several intense slip bands impinged. And it was found that, compared with the bicrystal specimens with a grain boundary parallel to loading axis, the bicrystal specimens with a grain boundary perpendicular to loading axis are quite favorable for the fatigue crack early growth along grain boundary. A PSB-GB model of fatigue crack initiation can be used to explain the initiation of the intergranular fatigue cracks.

The solubility of carbon in Mn-Fe alloy melts was measured experimentally at 1400 ℃. The solubility of carbon in Mn-Fe alloy melts (from pure Mn to pure Fe) can be cal-culated with following formula: Xc=0.1886+0.1 119XMn or XC=0.2703-0.1006XFe. By thermodynamical derivation and calculation, some thermodynamical data were obtained as follows: 1) in Fe-C and Fe-Mn-C systems, lnγ℃= -0.033, ε= 9.02, eg= 0.1534, in Mn-C and Mn-Fe-C systems,

Using thermal analysis, X-ray diffraction and color etching, the effects of Vand C content in Fe-5Cr-5Mo-5W-V-C alloy on crystallized phases and temperatures were investigated. A relationship between composition and solidified microstructure was obtained. The phase diagrams of pseudo-binary (Fe-5Cr-5Mo-5W-2C)-V and (Fe-5Cr-5Mo- 5W-3V)-C alloy systems and a proiccted diagram of liguid phase boundaries of (Fe-5Cr-5Mo-5W)-V-C alloy system were drawn. The results show that in order to obtain a large amount of dispersed and isolated eutectic VC, a high content of V is required for a low carbon content, and a low content of V is required when the C content is high.

30Cr2Ni4MoV and 30Cr2MoV steels presented blue brittleness near 230℃ and 180℃, respectively. The susceptibility of stress corrosion cracking (SCC) for this kind of steels in aqueous solution at various temperatures is very low except near blue brittleness temperature. Near blue brittless temperature, there is a strong interaction between the dynam-ic strain aging, which results in blue brittleness, and SCC, resulting in a steep enhancement of the susceptibility of SCC.

Acoustic emission was used to monitor the scale cracking and spalling of unimplanted and 1 × 1017 Y+ / cm2-implanted Ni3OCr directional solidification alloy samples that had been oxidized at 1000℃ for 20 h then furnace cooled to room temperature. The morphology of the remaining scale and spalled areas was observed by SEM. The AE results show that the cracking and spalling of the scales formed on transversal and longitudinal sam-ples are similar though their microstrutures are different. The cracking and spalling occoured on the scales of unhoplanted alloy. The crack initiated at the interfacial voids and grain boundaries, then propagated into the scale and produced spalling. The scale formed on Y+-implanted sample was significantly more resistant to fracture than that on unimplanted sample. AE results prove that Y+- implanation apparently decreases the amounts of the interfacial naws and reduces the mean size of the flaws.

In this paper, the heat damage fashions and mechanisms of the cast WC parti-cles in the laser clad ceramic-metal composite coating have been investigated systematically. It was demonstrated that the main heat damage fashion of the cast WC particles is the disso-lution and diffusion scorification. A half quantitative formula was derived to evaluate theheat damage extent of the WC particles.

This paper studied the effect of the welding-supporting technology on the quality of steel-aluminium solid to liquid bonding. The results show that welding-supporting technology can solve interface oxidation problem in the process of solid to liquid bonding, and interfacial strength in steel-aluminium solid to liquid bonding could increase substantially by immersing flux No.1 made up with halogenide.

A comprehensive examination was made on the structures and properties of Fe65Cr18Mo2Si1B14 and Fe62Crl8Mo2Si1B17 single-roll quenched ribbons. TEM revealed par-ticle-like amorphous second phase with size of tens of nanometer distributed in amorphous matrix, amount of which increased with boron concentration. Correspondingly, magnetic analysis and M6ssbauer spectrum indicated that the ribbons were composed of phases with different magnetic properties. A small amount of magnetic phase was detected to be dispersed in paramagnetic matrix and has high coercive force as single-domain particle. The quenched ribbons were brittle before annealing. A conclusion can be drawn that the boron segregation in eariy undercooled liquid during quenching results in the formation of amophous second phase, which brittlized the quenched ribbons.

Amorphous ribbons with the composition of Co66Fe4Mo2Sil6 have been isothermally annealed and isochronally annealed. During the isothermal annealing at 460 ℃, the initial permeability μi of the sample annealed for 45 min exhibited a maximum of 11.3 × 104 and the electron diffraction pattern revealed that the sample was still in the amorphous state. But it was observed that the magnetostriction λs varied from negative to positive value and ran through zero at about 45 min. So, it can be understood that the maximum of μi re-sulted from zero λs. In the process of isochronal annealing, a little α-Fe solid solution began to be produced in the sample annealed at 48O ℃. It was clear that the formation of a little amount of α-Fe phase resulted in a dramatic decrease in the magnetic properties.

The abrasive wear resistance of laser clad ceramic-metal composite coatings composed of different kinds, size and weight percent of WC particles has been investigated systematically, in which the single crystal WC, cast WC and cemented WC particles are used as the ceramic phases and Ni-base self-flux alloy as the matrix. The experimental results show that the abrasive wear resistance of the composite coatings is determined by the kinds, sizes, weight fractions of WC particles, and the changing tendency of the abrasive wear resist-ance of the weight fraction of the coatings depends on the type of WC particles.

The age-hardening characters of ZL109 alloy matrix composite reinforced by Al2O3-SiO2 fibre have been studied. It was found that ZL109 alloy matrix composite and ZL109 alloy had similar age-hardening curve, and the same precipitates. ZL109 alloy matrix composite exhibited higher hardness than ZL109 alloy in whole process of aging, and the hardness of the composite decreased more slowly than that of ZL109 alloy especially at high temperature (623 K). The calculation of activation energy showed that the GPB zone forma-tion of ZL109 alloy matrix composite needed more activation energy than that of ZLl09 alloy, while the S′ phase formation in ZL109 alloy matrix composite needed less activation energy than that in ZL109 alloy.