Is there any way to create a type alias for multiple traits?

While awaiting the stabilization of trait aliasing, you can use the trait-set crate. Here is an example of its use:

trait-set! {
    pub trait HashKey = Hash + Eq + Clone
}

PartialOrd and Display are traits. It has been discussed how to implement an alias but it was decided that it wasn't needed.

Instead, you can create a new trait with the traits you want as super traits and provide a blanket implementation:

use std::fmt::Display;

trait PartialDisplay: PartialOrd + Display {}
impl<T: PartialOrd + Display> PartialDisplay for T {}

fn print_min<T: PartialDisplay>(a: &T, b: &T) {
    println!("min = {}", if a < b { a } else { b });
}

fn main() {
    print_min(&45, &46);
    print_min(&"aa", &"bb");
}

RFC 1733 introduced the concept of a trait alias. When it is stabilized, you will be able to say:

#![feature(trait_alias)]

use std::fmt::Display;

trait PartialDisplay<Rhs = Self> = PartialOrd<Rhs> + Display;

fn print_min<T: PartialDisplay>(a: &T, b: &T) {
    println!("min = {}", if a < b { a } else { b });
}

fn main() {
    print_min(&45, &46);
    print_min(&"a", &"b");
}