Abstract
A comparison between the creep characteristics of an AZ91 magnesium alloy reinforced with 20 vol.% A₁₂O₃ short fibres and an unreinforced AZ91 matrix alloy shows that the creep resistance of the reinforced material is considerably improved compared to the matrix alloy. It is suggested that the creep strengthening in the composite arises mainly from the existence of a threshold stress and the load transfer effect. The values of the threshold stress in the creep of the composite at temperatures in the range from 373 to 673 K were estimated using standard methods. It is proposed that the threshold stress arises from an attractive interaction between mobile dislocations and Mg17(Al, Zn)₁₂ precipitates.

Key words
AZ91 magnesium alloy, metal matrix composite, creep, short fibre reinforcement, threshold stress, load transfer effect

Full text (486 KB)