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The microstructures and mechanical properties of Mg–6Al–0.6Zn alloy with Sm addition have been investigated. The results show that Sm can dramatically improve the yield strength and tensile strength of the alloy at 20–175 °C. With 0.5–2.0 wt.% Sm addition, the microstructure of alloy is remarkably refined. Spotted, high-melting point Al2Sm phases are found in the alloy. The microstructure and mechanical properties of the alloy with 1.5 wt.% Sm addition are found to be optimum.

The interaction between precipitation and recrystallization and its effect on the properties of the Cu−Ni−Si−Cr alloy during aging were discussed. The results show that the deformation results in much more dispersed precipitation of the phases. The precipitations have accelerating or retarding effects on the recrysiallization. On the formation and growth of recrystallization, the precipitated phases are coarsed or dissolved in front of grain boundaries following a re-precipitation in the recrystallization area.

A new method is proposed for the evaluation of the fracture toughness of case-hardened steel. The proposed method uses the concept of the elastic unloading compliance method. The principle of this method is that cracks with different lengths will show different elastic unloading compliance values, and vice versa. Lastly, the correctness of the proposed method is verified by measuring the elastic unloading compliance value using a series of specimens with given crack lengths.

Magnesium alloys as the emerging commercial metal structure material have excellent specific properties and stability, which is more and more important for researcher. The magnesium alloy of Mg-Al series, Mg-Zn series, Mg-RE series included Mg-Y series alloy, Mg-Gd-Y series alloy, Mg-RE-Zr series alloy, Mg-RE-Ag series alloy were summarized, the existing heat resistant magnesium alloy still exists insufficient heat resistance or poor comprehensive mechanical properties and processing property except heat-resistant magnesium alloys with Mg-RE. The development trends of heat resistant magnesium alloy were discussed and analyzed, Little multicomponent alloying is effective ways to improve the performance of heat resistant magnesium alloy, the alloy manufacturability was improved in order to industrialized production, and the melt purification, the casting and forming technology were researched in order to improve the comprehensive performance of heatresistant magnesium alloys. Keywordsreview; magnesium alloy; heat resistant; Mg-Zn; Mg-Al; Mg-RE