(1. 華南理工大學(xué) 材料科學(xué)與工程學(xué)院，廣州 510640；
2. 華南理工大學(xué) 機(jī)械與汽車(chē)工程學(xué)院，廣州 510640)
摘 要: 采用粉末冶金法制備多孔TiNi合金，并利用無(wú)壓熔滲鎂合金(AZ91D)工藝按設(shè)計(jì)要求制備具有近零膨脹特性且輕質(zhì)高強(qiáng)的AZ91D/TiNi復(fù)合材料。結(jié)果表明：AZ91D質(zhì)量分?jǐn)?shù)為8.20%~13.95%時(shí)，復(fù)合材料在一定的溫度范圍呈現(xiàn)近零膨脹行為，且熱膨脹系數(shù)實(shí)驗(yàn)值與混合定則理論預(yù)測(cè)值相近；多孔TiNi合金的負(fù)熱膨脹特性由相變引起的體積變化導(dǎo)致，而其復(fù)合材料呈現(xiàn)近零膨脹是由多孔TiNi基體產(chǎn)生的負(fù)熱膨脹被滲入的鎂合金相正熱膨脹抵消所致；引入鎂合金對(duì)復(fù)合材料基體合金的相組成和相變行為影響很小，但可顯著提高其強(qiáng)度，復(fù)合材料仍具有穩(wěn)定的線性超彈性。
關(guān)鍵字: TiNi合金；負(fù)熱膨脹；近零膨脹；復(fù)合材料；相變；力學(xué)性能
（1. School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China;
2. School of Mechanical and Automotive Engineering, South China University of Technology,
Guangzhou 510640, China）
Abstract:TiNi alloy based composites tailored by Mg alloy (AZ91D) were fabricated by powder metallurgy process combining with pressureless infiltration technique, which possess low density, high strength and the near-zero thermal expansion performance. The results show that, the AZ91D/TiNi composites exhibit near-zero thermal expansion performance at a certain temperature range when the AZ91D alloy mass fraction is between 8.20% and 13.95%. The experimentally measured coefficients of thermal expansion (CTEs) of the composites are close to those theoretically ones predicted by the rule-of-mixture (ROM). It is proposed that the negative thermal expansion (NTE) phenomenon of the porous TiNi alloy originates from the volume change accompanying the phase transformations of the TiNi alloy matrix. The near-zero thermal expansion performance of AZ91D/TiNi composites is attributed to the combination of the NTE produced by the porous TiNi alloy matrix and the positive thermal expansion provided by the infiltrated AZ91D alloy phase. The introduction of AZ91D alloy has little influence on the phase constituents and transformation characteristics of the bulk matrix, while significantly increasing the strength of the composite. At the meantime, the steady linear superelasticity of the composites is maintained.
Key words: TiNi alloy; negative thermal expansion; near-zero thermal expansion; composite; phase transformation; mechanical property
