2016-01-012024-05-13https://scholars.lib.ntu.edu.tw/handle/123456789/653725摘要：TiNi基形狀記憶合金(SMAs)是所有SMAs中性能最優越、生物相容性最好的，也因而廣為工程、醫工所應用。富鈦之TiNi SMAs (Ti含量在52 at.%以下)在一般之熔煉及熱處理下可得大量的TiNi相及少量之Ti2Ni相，其中TiNi相擁有形狀記憶特性，但Ti2Ni則是硬脆的相，故富鈦之TiNi SMAs因Ti2Ni之存在而使其性能較為劣化。最近本研究群把富鈦之TiNi SMAs利用快速凝固方法(RSP)製成厚度約為20μm之箔片，發現此富鈦SMAs之箔片產生奈米大小富鈦之G. P. zone的析出物，此G. P. zone析出物可維持到350°C左右仍不會變成Ti2Ni相。目前之研究已知此G. P. zone會促成先麻田散體R相的產生，且其形狀記憶特性相當優越，可逆之形狀回復應變高達6.4%。但此G. P. zone之存在對此等富鈦TiNi SMAs的機械性質，例如硬度、楊氏係數等之影響如何卻尚未得知。本計畫擬利用RSP製出來之富鈦TiNi箔片，經100~600°C不同溫度之時效後，利用奈米壓痕器來探討其機械性質(如硬度等)之變化，並與所測得之變態溫度及形狀記憶效應做一連結，以了解此G. P. zone對富鈦TiNi SMAs變態行為之影響。<br> Abstract: TiNi-based shape memory alloys (SMAs) have the best shape memory properties and biocompatibility among all SMAs and thus have many industrial/medical applications. According to Ni-Ti binary phase diagram, Ti-rich TiNi SMAs are mainly Ti50Ni50 phase with a little of Ti2Ni phase (particles) at room temperature if these alloys are fabricated by VAR/VIM melt. Here Ti50Ni50 phase can exhibit thermoelastic martensitic transformation and is regarded as the SMA, but Ti2Ni is a brittle intermetallic phase and can deteriorate the shape memory properties of Ti50Ni50 SMA. Therefore, Ti-rich TiNi SMAs are less used as industrial/medical applications as their performance is not so good as that of Ti50Ni50 or Ni-rich TiNi SMAs. Recently, in this research group, Ti-rich Ti51Ni49 SMAs were fabricated by rapid solidification process (RSP) to obtain &#8776; 20μm thickness ribbons. DSC tests indicated that as-spun and 200°C~600°C annealed ribbons have the transformation sequence of B2→R→B19’ in cooling and B19’→B2 in heating with a significant increase of the transformation temperatures for ribbons annealed at between 300°C and 400°C. TEM study revealed that there are lots of nanosize precipitates of Ti-rich Guinier-Preston (GP) zones existed in as-spun ribbon and in the ribbons annealed at temperature &#8804; 300°C. However, these nanosize GP zones disappear in the ribbons annealed at temperature &#8805; 400°C, in which nanosize disc-like Ti2Ni precipitates are formed. The shape memory effect (SME) tests at 238MPa tensile stress showed that the recoverable strain for as-spun and 200°C-annealed ribbons is 6.2% and 6.4%, respectively. These data indicate that Ti-rich Ti51Ni49 ribbons exhibit quite good SME as that of Ti50Ni50 or Ni-rich TiNi SMAs. However, the behaviors of precipitation hardening and other mechanical properties of Ti-rich SMAs ribbons induced by nanosize GP zones and disc-like Ti2Ni precipitates are still unclear. In this study, nanoindenter will be used to detect the ribbons hardness and other mechanical properties, such as Young modulus, to elucidate these unclear problems. At the same time, the detected mechanical properties will be related to the shape memory properties of Ti-rich SMAs exhibited in RSP ribbons.TiNi形狀記憶合金箔片析出硬化GP帶Ti2Ni析出物TiNi shape memory alloysribbonsprecipitation hardeningGuinier-Preston (GP) zonesTi2Ni precipitates