ORDER STATE AND STABILITY OF MARTENSITE IN AN AIR-QUENCHED Cu-Zn-Al ALLOY
(Department of Materials Science and Engineering,Central South University of Technology, Changsha 410083
* Anhui Institute of Technology, Hefei230069)
* Anhui Institute of Technology, Hefei230069)
Abstract: The martensite structure and its order state of Cu-18Zn-14Al(atomic fraction) alloy were studied by X-ray diffraction experiment and its intensity analysis. It is convinced that the M18R martensite with fairly perfect long-range order can be obtained by air-quenching the alloy. The atomic ordering configurations are two kinds of nearest neighboring (nn) order (K=even,H+K/2)=odd), i. e, Al-Cu atoms ordering and Zn-Cu atoms ordering, and one kind of next nearest neighboring (nnn) order (K=odd), i. e AlZn atoms ordering. The atomic distribution on the basic plane of the martensite is as follows:Ⅰ—14/25Al+11/25Cu,Ⅱ—Cu,Ⅲ—18/25Zn+7/25Cu. The martensite stabilization occurs in the alloy even on perfect ordering condition.
Key words: shape memory alloy Cu-Zn-Al alloy martensite ordering stabilization