相轉(zhuǎn)變行為的影響
(哈爾濱工業(yè)大學(xué) (威海) 材料科學(xué)與工程學(xué)院，威海264209)
摘 要: 利用充氫反應(yīng)球磨工藝制備氫化態(tài)Mg-3Ni-2MnO2儲(chǔ)氫復(fù)合材料，測(cè)試材料的吸放氫動(dòng)力性能，并利用Avrami指數(shù)研究?jī)?chǔ)氫材料吸放氫過(guò)程中相轉(zhuǎn)變行為特征。結(jié)果表明：在研究的溫度范圍內(nèi)，溫度越高，越有利于提高M(jìn)g-3Ni-2MnO2儲(chǔ)氫復(fù)合材料的吸放氫速度；在150~200 ℃范圍內(nèi)吸氫時(shí)，其Avrami指數(shù)由初始階段的1.0~1.5很快變?yōu)?.5，即儲(chǔ)氫材料很快進(jìn)入已形成相的增厚階段；在150~200 ℃范圍內(nèi)，溫度變化對(duì)吸氫相轉(zhuǎn)變影響不大，但影響相轉(zhuǎn)變速率；放氫過(guò)程中，根據(jù)Avrami 指數(shù)的變化，相轉(zhuǎn)變基本過(guò)程為形核長(zhǎng)大階段和新相繼續(xù)穩(wěn)定長(zhǎng)大階段(無(wú)新的晶核形成)，溫度變化同樣影響其放氫速率，但對(duì)其放氫過(guò)程的相轉(zhuǎn)變規(guī)律影響不大。
關(guān)鍵字: 儲(chǔ)氫材料；吸放氫；Avrami指數(shù)；形核長(zhǎng)大；動(dòng)力學(xué)
（School of Materials Science and Technology, Harbin Institute of Technology (Weihai), Weihai 264209, China）
Abstract:The hydrided Mg-3Ni-2MnO2 hydrogen storage materials were fabricated through ball-milling under hydrogen atmosphere. The hydrogenation and dehydrogenation dynamic properties were measured. The Avrami index was used to study the phase transformation behavior character. The results show that in the range of temperatures selected, the higher the temperature is, the faster the hydrogenation and dehydrogenation velocities of the fabricated Mg-3Ni-2MnO2 hydrogen storage materials are. When the materials is absorbed in the range of 150−200 ℃, the value of Avrami index can change quickly from 1.0−1.5 in the initial period to about 0.5, indicating that this period is for the new phase to increase thickness quickly. The change of temperature has no obvious effect on the phase transformation behavior character whereas affects the phase transformation velocity. During the dehydrogenation process, its phase transformation period includes nucleation and growth, and steady growth of the new phase with no new crystal nucleus appearing, according to the change of Avrami index. The change of temperature also affects the dehydrogenation velocity and has no obvious effect on the phase transformation behavior character.
Key words: hydrogen storage materials; hydrogenation and dehydrogenation; Avrami index; nucleation and growth; dynamics
