After retiring from the school, in 1991,1992 and 1998, upon invitation, Zhu toured several American universities, including the Eastman School of Music and The Hartt School at the University of Hartford, giving performances and introducing music pieces by contemporary Chinese composers. Zhu also dedicated herself to translating piano textbooks, such as The Pianist's Guide to Pedaling by Joseph Banowetz.

As a successful music educator, Zhu trained many Chinese pianists.

In an early interview that Zhu did with pianist Bao Huiqiao, Zhu said, "One should not focus on instant results, but take a long-term view.

"What I need to do is to provide my students with 'soil' and 'nutrition', just like gardeners planting flowers. The 'soil' and 'nutrition' will help my students grow for the rest of their lives," she said.

In the interview, Bao recalled that, when she was a student, she heard about Zhu and her two sisters, who were great pianists. During the 1980s, Bao became good friends with Zhu, as they were often invited to be judges of piano competitions held around the country.

"She was much older than me, but she looked very young. She impressed me with her modesty and work ethic," said Bao.

"It is very sad that my beloved teacher Zhu Yafen died about an hour ago. It's hard for me to believe it and I don't know how to express my grief," internationally celebrated pianist Lang Lang said in a post on microblogging platform, Sina Weibo, on Sunday. He studied with Zhu for six years.

"She was my teacher as long as I can remember. She was not only my piano teacher but also my life mentor," wrote Lang, describing Zhu as "the greatest, the most loving, caring and warmest teacher" who understood him the most. "I will keep on talking to you with my music. You will always be my spiritual guide," he wrote.

Lang can still remember the first time that he went to Zhu's home in Shenyang to learn to play the piano with her.

"I was three-and-a-half. I brought my toy gun with me. She told me to put the toy gun aside before playing the piano. That's how we started our first lesson," said Lang in an interview with China Daily on Monday. "Besides learning the piano, she also let me feed her cat and watch animated movies. I was relaxed whenever I took a piano lesson with her."