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Cu-Al-Ni 계 형상기억리본 제조시 냉각속도에 따른 미세조직 및 변태특성
장우양,이영수,이은구 한국열처리공학회 2000 熱處理工學會誌 Vol.13 No.4
The microstructural change and transformation characteristics with cooling rate i.e. wheel speed were investigated in 82.8wt%Cu-12.8wt%Al-4.3wt%Ni SMA ribbons fabricated by melt-spinning. The thickness and width of ribbon were decreased with increasing wheel speed, while the uniformity of it was improved. At same wheel speed, the grain size of the contact surface of ribbon was smaller than that of free surface. The mean grain size was decreased with increasing wheel speed, resulted in obtaining grains with 3㎛ in mean diameter in the wheel speed of 30m/s. However, micro-voids and cracks at grain boundary could be observed at higher wheel speed. M_s, and A_s temperatures were decreased, and M_s∼M_f and A_s∼A_f temperature ranges were broadened with increasing wheel speed. All the ribbons were retained the ordered DO₃due to rapid cooling, the volume fraction of it was increased with increasing wheel speed.
Cu - Zr 이원계 합금에서 화학조성 및 열싸이클링에 따른 마르텐사이트 특성의 열분석학적 연구
장우양,조민성,이재현,이영수,강조원,곽사호 ( W . Y . Jang,J . Van Humbeerk,M . S . Jo,J . H . Lee,Y . S . Lee,J . W . Kang,S . H . Gwak ) 한국열처리공학회 1998 熱處理工學會誌 Vol.11 No.2
N/A The effects of chemical composition and thermal cycling on the martensitic transformation characteristics in Cu-rich, equiatomic and Zr-rich CuZr binary alloys have been studied by calorimetry. Only martensite could be indentified in equiatomic Cu_(49.9)Zr_(50.1) alloy, while Cu_(10)Zr_7 and CuZr₂intermetallic compounds as well as martensite were formed by rapid cooling from the melts in Cu-rich Cu_(52.2)Zr_(47.5) alloy and Zr-rich Cu_(48.4)Zr_(51.6) alloy, respectively. The M_s temperature of Cu_(49.9)Zr_(50.1) was 156℃ but those of Cu_(52.5)Zr_(47.5) and Cu_(48.4)Zr_(51.6) alloys, being 109℃ and 138℃, were lower than that of equiatomic Cu_(49.9)Zr_(50.1) alloy. In all the alloys, the M_s temperature has fallen but the A_s temperature has risen, resulting in widening of the transformation hysteresis with thermal cycling. The anomalous characteristics in the transformation temperature are due to the presence of the intermetallic compounds i.e. Cu_(10)Zr_7 and CuZr₂formed by an eutectoid reaction during thermal cycling in the temperature range between -100℃<T_c<400℃.
Cu-Al-Ni계 합금 선재의 의탄성 거동에 미치는 미세조직의 영향
장우양,김경훈,은상원,강조원 조선대학교 생산기술연구소 2005 生産技術硏究 Vol.27 No.spec
In order to realize the psuedoelastic behavior of polycrystalline Cu-Al-Ni based alloy, Cu-Al-Ni based alloy rod with unidirectional solidification structure was fabricated by heated-mold continuous casting process. When the cast rod was betatized at the elevated temperature above 700℃, the Y₂ phase is gradually dissolved into the matrix so that the volume fraction of the Y₂ phase was decreased. The compressed specimen was completely recovered upon unloading, resulting in pseudoelastic behavior. The pseudoelastic strain of 10 % could be obtained in cast rod betatized above 700 ℃. However, the stress-strain curves for compression test were not same with betatizing temperature: the stress-strain curves of the specimen betatized at 600 ℃ and 700 ℃ were linear but those of the specimen betatized at 800 ℃ and 900 ℃ were not linear.