Effect of Co Addition on the Microstructure, Martensitic Transformation and Shape Memory Behavior of Fe-Mn-Si Alloys
- PDF / 2,713,510 Bytes
- 14 Pages / 593.972 x 792 pts Page_size
- 80 Downloads / 234 Views
INTRODUCTION
THE shape memory effect (SME) associated with the austenite (c)-e martensitic transformation has been reported in a number of Fe-based alloy systems. Enami et al.[1] were the first to report SME in Fe-18.5 pct Mn binary alloy, although, the amount of shape recovery observed in this alloy was very limited. The extent of recovery in these binary Fe-Mn alloys improves with increasing Mn content up to 20 pct. However, at higher Mn contents (more than 23 wt pct) the parent c-phase gets stabilized due to paramagnetic to anti-ferromagnetic transition.[2] It was Gartstein et al.[3] who first suggested that addition of ternary elements such as Si or Co can widen the temperature range of c-e transformation and increase the amount of e martensite. They also pointed out that such ternary alloying will not substantially affect the martensite transformation start temperature (MS) but will strongly reduce the paramagnetic to antiferromagnetic transition temperature, Ne´el transition temperature (TN), of these alloys. Subsequent to that a few years later, Sato et al.[4] reported that addition of small amount of Si (~1 pct) in single-crystal Fe-30 pct
BIKAS C. MAJI and MADANGOPAL KRISHNAN, Scientific Officers, are with the Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 085, India. Contact e-mail: [email protected] M. SUJATA, Scientist, is with the Materials Science Division, National Aerospace Laboratories, Bangalore 560 017, India. GOUTHAMA, Professor, is with the Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur, Kanpur 208 016, India. RANJIT K. RAY, Visiting Scientist, is with the R & D Division, Tata Steel, Jamshedpur 831 007, India. Manuscript Submitted February 23, 2012. METALLURGICAL AND MATERIALS TRANSACTIONS A
Mn alloy can improve the shape recovery to a great extent. Based on this idea, Murakami et al.[5] developed the first polycrystalline Fe-Mn-Si shape memory alloys (SMAs), which could show recoverable strain more than 1.7 pct. Thereafter several studies have been carried out on these Fe-Mn-Si based SMAs to improve their recoverable strain by thermo-mechanical training,[6,7] corrosion resistance by alloying[8] and the strength of the c-matrix either by solid solution[9] or precipitation hardening.[10,11] However, so far only a very limited numbers of studies are available in published literature on Fe-Mn-Co SMAs. Hamers and Wayman[12] were the first to study the shape memory behavior of Fe-Mn-Co alloys in a limited composition range of Fe-(25-30)Mn-(5-8)Co and found that the amount of recovery in these alloys is comparatively lower than Fe-Mn-Si alloys. Contrary to their results, Reyhani et al.[13] studied the shape memory behavior in Fe-(14-26)Mn-9Co-5Ni alloys and concluded that the amount of shape recovery in these alloys is comparable to that of Fe-Mn-Si or Fe-Mn-Si-Cr-Ni SMAs. Jiang et al.[14] have examined the effect of Co addition on the martensitic transformation and shape recovery of Fe-Mn-Si-Cr-Ni alloys. These authors[14] have reported that C
Data Loading...
