【摘要】：本文根據(jù)Ti-V-Al合金屈服強度低,難以滿足高性能連接要求的問題提出了B摻雜的合金化方法,提高合金的強度。采用掃描電鏡,X射線衍射儀,金相顯微鏡,掃描示差量熱分析儀,室溫拉伸儀,透射電鏡觀察等設備系統(tǒng)研究了Ti-V-Al-B形狀記憶合金的組織結構與應變恢復特性,分析了B含量及熱機械處理對Ti-V-Al合金組織結構,馬氏體相變,力學性能,形狀記憶效應的影響規(guī)律和機制。研究表明,固溶態(tài)Ti-V-Al-B合金的室溫組織為正交結構的α"馬氏體相,B的加入并未改變合金的室溫組織。650℃退火時,合金基體由α"和少量α相組成,隨著退火溫度的升高,合金的中的α相體積逐漸增大,數(shù)量逐漸減少,分布變得不均勻。當B元素含量低于0.01at%時,合金中無第二相生成,隨著B元素的增加,合金中逐漸生成斜方結構的纖維狀TiB相,并由彌散分布于基體中間變?yōu)橼呄蛴谘泳Ы绶植�。B的摻雜有效減小了合金的晶粒尺寸,固溶態(tài)合金晶粒由Ti-13V-3Al的284μm下降到了(Ti-13V-3Al)99。9B0.1的75μm左右。隨著B的添加(Ti-13V-3Al)_(100-x)B_x合金的逆相變溫度先下降后上升,對(Ti-13V-3Al)_(99.9)B_(0.1)合金進行650℃退火,合金無法觀察到逆相變峰,隨著退火溫度的升高,逆相變峰出現(xiàn)且逆相變溫度逐漸趨近于固溶態(tài)(Ti-13V-3Al)_(99.9)B_(0.1)合金。B的加入及熱機械處理都有效提升了合金的相變循環(huán)穩(wěn)定性。經(jīng)五次熱循環(huán)后,(Ti-13V-3Al)_(99.9)B_(0.1)合金的逆相變溫度下降了65.4℃,熱機械處理后的(Ti-13V-3Al)_(99.9)B_(0.1)合金逆相變溫度僅下降了26.89℃,隨著B含量的增加固溶態(tài)Ti-V-Al-B合金的屈服強度,抗拉強度和延伸率呈現(xiàn)先上升后下降的趨勢,當B含量為0.1at%時,合金的屈服強度合抗拉強度達到711MPa和987MPa,比未摻雜B元素的Ti-13V-3Al合金高了51.9%和39%。隨著退火溫度的升高,合金的屈服強度逐漸下降,延伸率逐漸升高。隨著固溶時間的增長,合金的屈服強度及抗拉強度逐漸增加,延伸率逐漸下降。B元素的加入有效改善了合金的形狀記憶效應,合金的可恢復應變隨B含量的增加上升后下降,當B含量為1at%時,完全可恢復應變達到4%,預應變?yōu)?%時,合金的可恢復應變達到5.01%。隨著退火溫度的增加,合金的記憶效應逐漸下降,700℃時記憶效應達到最好。
[Abstract]:In this paper, according to the problem that the yield strength of Ti-V-Al alloy is low and it is difficult to meet the requirements of high performance bonding, a B-doping alloy method is proposed to improve the strength of the alloy. The microstructure and strain recovery characteristics of Ti-V-Al-B shape memory alloy were systematically studied by means of scanning electron microscope, X-ray diffractometer, metallographic microscope, scanning differential thermal analyzer, room temperature extensor and transmission electron microscope. The effects of B content and thermomechanical treatment on the microstructure, maraging, mechanical properties and shape memory effect of Ti-V-Al alloy were analyzed. The results show that the microstructure of solid solution Ti-V-Al-B alloy at room temperature is 偽 "marsite phase with orthogonal structure at room temperature, and the addition of B does not change the room temperature microstructure of the alloy. When annealed at 650 鈩，

本文編號：2509144