"iron heart" is a correct and usable phrase in written English.
It is used to describe a person who is emotionally distant or unyielding, and who is difficult to reach or touch emotionally. For example: "Despite many attempts to connect with him, she had to admit he had an iron heart."
No words, no tears, no prayers, from his gory victim, seemed to move his iron heart from its bloody purpose.
"HHhH" is about the rise and fall of Reinhard Heydrich, the monster whom even Hitler called "the man with the iron heart".
The final pair was by the coveted Japanese specialty house Iron Heart ($350), and made of 21-ounce denim, among the thickest you can buy.
It results from too much iron in the body and can cause diabetes if it kills insulin-producing cells in the pancreas, or "iron heart" if too much of the metal accumulates in that organ and causes cardiac arrest.
Jamie Dornan and Cillian Murphy star as two of the allied special operatives assigned with taking down the SS-Obergruppenführer who Hitler called "the man with the iron heart".
Maybe then you'll be ready for one of the most impressive pieces in the store: a rawhide-thick Iron Heart denim jacket in an inky black, which with wear will turn indigo, an "atari" fade ($490).
As with many things at Self Edge, the Iron Hearts were made with motorcyclists in mind, demanding men far tougher than I am.
But writers can describe iron hearts in different ways: hearts and minds might be "steeled by courage, love, principles, and maxims, or rancor, habit, scorn and revenge" (186; emphasis in original).
At the commissioning Field Marshal Wilhelm von Hahnke spoke, saying, "old wisdom, si vis pacem, para bellum he who wants peace shall be prepared for war...may the guns and machines of the Yorck be operated only by men with iron hearts and an iron will, men who know no other order than to put their lives at risk when the might, the greatness and honor of the German people are being fought for".
Only those of a cast-iron heart wouldn't have felt a flutter of emotion.
Once the valentines started, there was no stopping them: a heart-shaped puzzle; handbags and other enthusiasms of Ruth's; a cast-iron heart that could be rung like a bell.
