Effect of Zn on age hardening, microstructure, defects and electronic structurein matrix of Al-Li-Cu-Mg-Zr alloy has been investigated. The addition of Zn to the alloysignincantly influences the precipitation, aging and positron annihilation parameters. TheZn-containing alloys exhibit stronger hardening tendency and higher value of hardness.Moreover, the presence of Zn may delay the growth of δ' particles and stimulate the precipita-tion and uniform distribution of S' phase. After aged for along time, coarse lath-like phasesrich in Zn would precipitate both in matrix and at grain boundaries in the Zn-containing al-loys.

An addition of 0.005 wt-% Ca to 60CrMnCuV steel may improve markedlythe impact toughness, and restricts the intergranular fracture. AES analysis shows that Casegregates markedly at the austenite grain boundaries, and restricts the segregation of S ataustenite grain boundaries. It is belived that an important reason to improve the toughnessmay attributes to the interactions of Ca and S segregations at the grain boundaries ofaustenite

Effect of mischmetal on the reaction between iron panels and Zn+5wt-%Alliquid alloy during hot dipping at 450℃ was investigated. After about 2--4s interval, anintermetallic layer may form and grow, and it will be postponed to 64-128s if themischmetal added in liquid alloy bath. The structure of the intermetallic layer has been stu-died by SEM, EDX, XRD, EMPA and TEM. The AES record in depth analysis shows thatthe rare earth elements segregated at the interface between iron panel and liquidZn+5wt-% Al alloy. The effect of mischmetal addition was discussed.

The activity interaction parameters between alloying elements and P in liquidFe at 1873K were obtained by the thermodynamic calculation. The calculated values arebasically accordant with experimental ones.

The property and mechanism of corrosion fatigue (CF) crack propagation ofmartensitic and bainitic 40CrMnSiMoVA (GC-4) ultra-high strength steel was investigated.There is a platform region on CF crack propagation curve of the GC-4 steel with differentmicrostructure in 3.5% NaCl solution, which is similar to its stress corrosion crackingbehaviour. The CF crack propagation rate (in platform region) of martensitic GC-4 steel ismuch higher than that of bainitic one. Through fracture surface examination and theoreticalanalysis, it is revealed that hydrogen embrittlement plays an important role in the CF pro-cess of GC-4 steel.

Study was carried out of the effect of overlapping or not on the fatiguemacro-crack initiation on the notch root of 40Cr steel specimens treated by newly developedtechnique of laser local hardening. The resistance to fatigue macro-crack initiation may bemade by grain refining, marstrengthening and residual compressive stress. In the light ofbehaviour of fatigue fracture, the superiority of local laser hardening to improve the fatigueresistance is in the range of low stress amplitude and high cycles. The morphology of the frac-ture surface in the hardened specimen is a mixed one of transgranular and intergranular.

Supersaturated solid solutions have been obtained by mechanical alloying inCu-Fe system which are immiscible at room temperature. The fcc phase range has been ex-tended to x>35 at.-% Cu. High resolution electron microscope images show that thereexist N-W orientation relationship,i.e. < 001 > α//<110>γ and < 110 > α// < 111 > γbetween bcc phase and fcc phase after 3h milling. It is quite possible that inverse martensitictransformation has occurred during mechanical alloying and the extension of fcc phase rangeclosely relates to this transformation. The fracture and refinement of particles, and cold-weld-ing images were also observed by using a high resolution electron microscope. After 60h me-chanical alloying, homogenous nanocrystals with particle size about 10 nm formed.