Effect of Solid Solution Temperature on the Cold Working Properties of Cu-Al-Mn Shape Memory Alloys

The cold working properties of the Cu-17.55Al-9.84Mn (mole fraction) and Cu-19.1Al-9.9Mn shape memory alloys were studied by means of optical microscopy, scanning electron microscopy, X-ray diffractometer and room temperature compression tester. The results show that the solid solution temperature had a significant effect on the cold working properties of the alloy containing 17.55% Al, but a weak effect on that of the alloy containing 19.1% Al. After solid solution above 700 ℃, β phase or 18R martensite with low order degree was obtained at room temperature because the alloy containing 17.55% Al owned low aluminum content, thus the stress easily made β phase or 18R martensite transform into martensite or martensite reorient, so the cold working properties were much higher than the alloy in two phase α and β. The cold working properties of the alloy containing 19.1% Al were far lower than those of the alloy containing 17.55% Al as its structure was mainly composed of β phase with high order degree at room temperature.